impetuosity (n.) — improve (v.)
early 15c., "violent movement, rushing," from Old French impetuosité (13c.) and directly from Medieval Latin impetuositatem (nominative impetuositas), from Late Latin impetuosus "impetuous, violent" (see impetuous).ETD impetuosity (n.).2
mid-14c., from Old French impieté "impiety, wickedness" (12c.) or directly from Latin impietatem (nominative impietas) "irreverence, ungodliness; disloyalty, treason," noun of quality from impius "irreverent" (see impious).ETD impiety (n.).2
1670s, "act of impinging;" see impinge + -ment.ETD impingement (n.).2
1530s, "fasten or fix forcibly," from Latin impingere "drive into, strike against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pangere "to fix, fasten" (from PIE root *pag- "to fasten"). The sense of "encroach, infringe" is attested by 1738. Related: Impinged; impinging; impingent.ETD impinge (v.).2
1590s, "irreligious, lacking reverence for God," from Latin impius "without reverence, irreverent, wicked; undutiful, unpatriotic," from assimilated form of in- "not, opposite of" (see in- (1)) + pius (see pious). Related: Impiously; impiousness.ETD impious (adj.).2
1650s, from imp + -ish. Related: Impishly; impishness.ETD impish (adj.).2
1530s, from Late Latin implacabilitas, from Latin implacabilis "unappeasable" (see implacable).ETD implacability (n.).2
"unappeasable," early 15c., from Old French implacable, from Latin implacabilis "unappeasable," from assimilated form of in- "not, opposite of" (see in- (1)) + placabilis "easily appeased" (see placate). Related: Implacably.ETD implacable (adj.).2
1570s, "manner of being implanted," from French implantation, noun of action from implanter "to insert, engraft" (see implant (v.)). From c. 1600 as "act of implanting;" in embryology from 1902.ETD implantation (n.).2
1540s, "to plant in" (abstractly, of ideas, emotions, etc.), from French implanter "to insert, engraft" (alongside Old French emplanter "to plant"), literally "plant in," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + planter "to plant" (see plant (n.)). Meaning "surgically implant (something) in the body" is from 1886, originally of teeth. Implanted is attested earlier, from early 15c., probably based on Medieval Latin implantus. Related: Implanting.ETD implant (v.).2
1890, "thing implanted;" 1941 as "action of implanting," from implant (v.). Related: Implants, which is attested by 1981 as short for breast implants (1976).ETD implant (n.).2
"not having an appearance of truth or credibility," 1670s, from assimilated form of in- "not, opposite of" (see in- (1)) + plausible. Earlier it meant "not worthy of applause" (c. 1600). Related: Implausibly.ETD implausible (adj.).2
1630s, from implausible + -ity.ETD implausibility (n.).2
mid-15c., "supplementary payment, amount needed to complete repayment," from Late Latin implementem "a filling up" (as with provisions), from Latin implere "to fill, fill up, make full; fatten; fulfill, satisfy," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plere "to fill" (from PIE root *pele- (1) "to fill"). Sense of "workman's tool, utensil of a trade, things necessary to do work" is 1530s. The underlying connection of the senses is "whatever may supply a want, that which fills up a need." Related: Implemental; implements.ETD implement (n.).2
"to complete, perform, carry into effect," 1707, originally chiefly in Scottish English, where the noun was a legal term meaning "fulfillment," from implement (n.). It spawned implementation, which is recorded by 1913. Related: Implemented; implementing.ETD implement (v.).2
"to fill, pervade," 1862, from Latin impletus, past participle of implere "to fill, fill up" (see implement (n.)). OED says U.S. Related: Impleted; impleting.ETD implete (v.).2
"action of filling," 1580s, from Late Latin impletionem, noun of action from stem of implere "to fill, fill up" (see implement (n.)).ETD impletion (n.).2
"intricate, complicated," 1710, from Latin implexus "interwoven, entwined," past participle of implectere, from assimilated form of in- "in" (from PIE root *en "in") + plectere "to plait, twine, braid" (from suffixed form of PIE root *plek- "to plait"). Used by 18c. critics in reference to plots.ETD implex (adj.).2
late 14c., implien, emplien "to enfold, enwrap, entangle" (the classical Latin sense), from Old French emplier, from Latin implicare "involve, enfold, entangle," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait").ETD imply (v.).2
Meaning "to involve something unstated as a logical consequence" first recorded c. 1400; that of "to hint at" is from 1580s. Related: Implied; implying. The distinction between imply and infer is in "What do you imply by that remark?" but, "What am I to infer from that remark?" Or, as Century Dictionary puts it, "An action implies ability or preparation, but involves consequences."ETD imply (v.).3
"intended but not expressed," 1520s, past-participle adjective from imply (v.). Implied powers in a constitutional sense is attested from 1784.ETD implied (adj.).2
"tending to implicate," c. 1600, from implicate + -ive. Related: Implicatively (1570s).ETD implicative (adj.).2
early 15c., "action of entangling," from Latin implicationem (nominative implicatio) "an interweaving, an entanglement," noun of state from past participle stem of implicare "involve, entangle; embrace; connect closely, associate," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). Meaning "that which is implied (but not expressed), inference drawn from what is observed" is from 1550s.ETD implication (n.).2
see implication.ETD implications (n.).2
early 15c., "to convey (truth) in a fable," from Latin implicatus, past participle of implicare "to involve, entwine, entangle, embrace," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). From c. 1600 as "intertwine, wreathe." Meaning "involve (someone) in a crime, charge, etc.; show (someone) to be involved" is from 1797. Related: Implicated; implicating.ETD implicate (v.).2
1590s, "implied, resting on inference," from French implicite and directly from Latin implicitus, later variant of implicatus "entangled, confused, involved," past participle of implicare "entangle, involve," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + plicare "to fold" (from PIE root *plek- "to plait"). From c. 1600 as "resulting from perfect confidence (in authority), unquestioning" (especially of faith).ETD implicit (adj.).2
c. 1600, "by implication," from implicit + -ly (2). From 1640s as "unquestioningly."ETD implicitly (adv.).2
1870 (implied in imploded), originally of consonants, a back-formation from implosion. In the sense of "collapse violently inward due to deep-sea pressure" (originally in reference to thermometer bulbs), it is attested by 1881. Related: Imploding.ETD implode (v.).2
c. 1500, from French implorer and directly from Latin implorare "call on for help, beseech, beg earnestly," with a literal sense probably of "plead tearfully, invoke with weeping," from assimilated form of in- "on, upon" (from PIE root *en "in") + plorare "to weep, cry out," a word of unknown origin. Related: Implored; imploring; imploringly; imploration.ETD implore (v.).2
"a bursting inward, a sudden collapse," 1829, modeled on explosion, with assimilated form of in- (2) "into, in, on, upon" (from PIE root *en "in").ETD implosion (n.).2
In early use often in reference to effect of deep sea pressures, or in phonetics. Figurative sense is by 1960.ETD implosion (n.).3
1876, originally in linguistics, probably from implode on the model of explosive; implosive is attested in French and German from 1860s.ETD implosive (adj.).2
"not according to good policy," c. 1600, from assimilated form of in- (1) "not, opposite of" + politic (adj.) "judicious." Related: Impoliticly. Impolicy "quality of being impolitic" is attested from 1747.ETD impolitic (adj.).2
1670s, from impolite + -ness.ETD impoliteness (n.).2
1610s, "unrefined, rough," from Latin impolitus "unpolished, rough, inelegant, unrefined," from assimilated form of in- "not, opposite of" (see in- (1)) + politus "polished" (see polite). Sense of "discourteous, uncivil, unpolished in manners" is from 1739. Related: Impolitely.ETD impolite (adj.).2
1794, "weightless," from assimilated form of in- (1) "not, opposite of" + ponderable (see ponder). Figurative use, "unthinkable," from 1814. As a noun from 1829, originally meaning heat, light, electricity, etc., as having no weight. Related: Imponderably; imponderability. Imponderous is attested from 1640s as "without weight." Imponderabilia "unthinkable things collectively" is attested from 1835.ETD imponderable (adj.).2
mid-15c., "significant, of much import, bearing weight or consequence," from Medieval Latin importantem (nominative importans) "important, momentous," present-participle adjective from importare "be significant in," from Latin importare "bring in, convey, bring in from abroad," from assimilated form of in- "into, in" (from PIE root *en "in") + portare "to carry," from PIE root *per- (2) "to lead, pass over." The meaning "pretentious, pompous" is from 1713. Related: Importantly. Compare import (v.) and (n.).ETD important (adj.).2
c. 1600; see import (v.) + noun ending -ation.ETD importation (n.).2
"the quality of having consequence," c. 1500, from French importance or directly from Medieval Latin importantia "importance," from importantem "important" (see important).ETD importance (n.).2
1580s, "consequence, importance;" 1680s, "that which is imported;" both from import (v.).ETD import (n.).2
early 15c., "signify, show, bear or convey in meaning," from Latin importare "bring in, convey, bring in from abroad," from assimilated form of in- "into, in" (from PIE root *en "in") + portare "to carry," from PIE root *per- (2) "to lead, pass over." In English, the sense of "bring from another state or land," especially "bring in goods from abroad" is recorded by 1540s. As "be important" from 1580s. Related: Imported; importing.ETD import (v.).2
1520s, from importune + -ate (1), or else from Medieval Latin importunatus, past participle of importunari "to make oneself troublesome." Related: Importunately (mid-15c.). Earlier adjective was importune (c. 1400).ETD importunate (adj.).2
"persistence, insistence; over-eagerness," early 15c., from Old French importunité (14c.), from Latin importunitatem (nominative importunitas) "unsuitableness; unmannerliness, unreasonableness, incivility," from importunus "unfit, troublesome" (see importune).ETD importunity (n.).2
"harass with solicitation, demand persistently," 1520s, back-formation from importunity, or else from French importuner, from Medieval Latin importunari "to make oneself troublesome," from Latin importunus "unfit, unfavorable, troublesome," literally "having no harbor" (thus "difficult to access"), from assimilated form of in- "not, opposite of" (see in- (1)) + portus "harbor" (see port (n.1)). Related: Importuned; importuning. As an adjective from early 15c. Portunus was the Roman deity of harbors; hence Portunium "temple of Portunus."ETD importune (v.).2
late 14c., "to lay (a crime, duty, obligation, etc.) to the account of," from Old French imposer "put, place; impute, charge, accuse" (c. 1300), from assimilated form of in- "into, in" (from PIE root *en "in") + poser "put, place" (see pose (v.1)). From c. 1500 as "apply authoritatively." Sense of "lay on as a burden, inflict by force or authority" first recorded 1580s. Related: Imposed; imposer; imposing.ETD impose (v.).2
"impressive in appearance or manner," 1786, present-participle adjective from impose (v.). Related: Imposingly.ETD imposing (adj.).2
late 14c., "a tax, duty, tribute," from Old French imposicion "tax, duty; a fixing" (early 14c.), from Latin impositionem (nominative impositio) "a laying on," noun of action from past participle stem of imponere "to place upon," from assimilated form of in "into, in" (from PIE root *en "in") + ponere "to put, place" (past participle positus; see position (n.)). Sense of "the act of putting (something) on (something else)" is from 1590s. Meaning "an act or instance of imposing" (on someone) first recorded 1630s, a noun of action from impose, which is unrelated to the earlier word.ETD imposition (n.).2
late 14c., from Old French impossible (14c.), from Latin impossibilis "not possible," from assimilated form of in- "not, opposite of" (see in- (1)) + possibilis (see possible). Weakened sense of "unable to be accomplished or tolerated" is from mid-19c. Related: Impossibly.ETD impossible (adj.).2
late 14c., "quality of being impossible," from impossible + -ity; perhaps from or modeled on Old French impossibilité (14c.). Meaning "an impossible thing or occurrence" is from c. 1500. Sometimes in English 15c.-18c. it meant "inability, impotence," after a use of Medieval Latin impossibilitas.ETD impossibility (n.).2
"belief in social reforms (or other ideas) that could not practically be attained or accomplished," 1885, from impossible + -ism. Related: Impossibilist.ETD impossibilism (n.).2
"tax, duty," 1560s, from French impost (15c., Modern French impôt), from Medieval Latin impostum "a tax imposed," noun use of neuter of Latin impostus, contracted form of impositus, past participle of imponere "to place upon, impose upon" (see impostor). Compare depot. As an architectural term, 1660s, from French imposte (16c.), from Italian imposta, from the same Latin source.ETD impost (n.).2
1580s, "swindler, cheat," from French imposteur (16c.), from Late Latin impostor "a deceiver," agent noun from impostus, contraction of impositus, past participle of imponere "place upon, impose upon, deceive," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + ponere "to put, place" (past participle positus; see position (n.)). Meaning "one who passes himself off as another" is from 1620s. Related: Impostrous. For a fem. form, Bacon uses French-based impostress (1610s) while Fuller, the church historian, uses Latinate impostrix (1650s).ETD impostor (n.).2
"act of willfully deceiving others," 1530s, from French imposture or directly from Late Latin impostura "deceit," from impostus (see impost (n.)). Related: Imposturous.ETD imposture (n.).2
"undrinkable," c.1600, from assimilated form of in- (1) "not" + potable, or else from Late Latin impotabilis.ETD impotable (adj.).2
early 15c., "physical weakness," also "poverty," from Old French impotence "weakness" (13c.), from Latin impotentia "lack of control or power," from impotentem "lacking control, powerless" (see impotent). In reference to a complete want of (male) sexual potency, from c. 1500. The figurative senses of the word in Latin were "violence, fury, unbridled passion," via the notion of "want of self-restraining power," and these sometimes were used in English. Related: Impotency.ETD impotence (n.).2
late 14c., "physically weak, enfeebled, crippled," from Old French impotent "powerless, weak, incapable of doing," from Latin imponentem (nominative impotens) "lacking control, powerless, feeble; lacking self-control," from assimilated form of in- "not, opposite of" (see in- (1)) + ponentem (nominative potens) "potent" (see potent).ETD impotent (adj.).2
Meaning "having no power to accomplish anything" is from mid-15c.; that of "completely lacking in sexual power" (of males) is from mid-15c. Middle English also had a native term for this: Cunt-beaten (mid-15c.). The figurative sense in Latin was "without self-control, headstrong, violent, ungovernable, lacking self-restraint," which sometimes is found in English (OED cites examples from Spenser, Massinger, Dryden, and Pope). Related: Impotently.ETD impotent (adj.).3
early 15c., "to shut up in a pen or pound," from assimilated form of in- "into, in" (from PIE root *en "in") + pound (n.). Originally of cattle seized by law. Related: Impounded; impounding.ETD impound (v.).2
1660s; see impound + -ment. Earlier in the same sense were impoundage (1610s), impounding (1550s).ETD impoundment (n.).2
1550s, from Anglo-French empoverissement, from empoverir; see impoverish + -ment.ETD impoverishment (n.).2
early 15c., empoverischen, from Old French empoveriss-, stem of empoverir, from em- + povre "poor" (see poor (adj.)). In the same sense Middle English had also empover (early 15c., from Old French enpoverir), also poverished "made poor" (late 14c.). Related: Impoverished; impoverishing.ETD impoverish (v.).2
1823, from assimilated form of in- (1) "not, opposite of" + practical (adj.). Impracticable in the same sense dates from 1670s; unpractical is rare. Related: Impractically.ETD impractical (adj.).2
1843; see impractical + -ity.ETD impracticality (n.).2
"incapable of being done, not to be done by available means," 1670s, from assimilated form of in- (1) "not, opposite of" + practicable. Earlier in a sense of "impassable" (1650s). Related: Impracticably; impracticability.ETD impracticable (adj.).2
"call down by prayer" (typically of curses or malevolent desires), 1610s, probably a back-formation from imprecation. Related: Imprecated; imprecating; imprecatory (1580s).ETD imprecate (v.).2
mid-15c., "a curse, cursing," from Latin imprecationem (nominative imprecatio) "an invoking of evil," noun of action from past participle stem of imprecari "invoke, pray, call down upon," from assimilated form of in- "into, in, within" (from PIE root *en "in") + precari "to pray, ask, beg, request" (from PIE root *prek- "to ask, entreat"). "Current limited sense is characteristic of human nature" [Weekley].ETD imprecation (n.).2
1804, from assimilated form of in- (1) "not, opposite of" + precise. Earlier was unprecise (1756). Related: Imprecisely.ETD imprecise (adj.).2
"inexactness," 1771, from assimilated form of in- (1) "not, opposite of" + precision.ETD imprecision (n.).2
c. 1600, "to fill with an ingredient, spirit, etc.;" 1640s as "make (a female) pregnant," from Late Latin impraegnatus "pregnant," past participle of impraegnare "to render pregnant," from assimilated form of in- "into, in" (from PIE root *en "in") + praegnare "make pregnant" (see pregnant). Earlier in same sense was impregn (1530s), which OED marks as "now only in poetic use."ETD impregnate (v.).2
late 14c., "making or becoming pregnant," from Old French impregnacion or directly from Late Latin impregnationem (nominative impregnatio), noun of action from past participle stem of impraegnare "to impregnate" (see impregnate).ETD impregnation (n.).2
early 15c., imprenable "impossible to capture," from Old French imprenable "invulnerable," from assimilated form of in- "not, opposite of" (see in- (1)) + Old French prenable "assailable, vulnerable" (see pregnable). With restored -g- from 16c. Related: Impregnably.ETD impregnable (adj.).2
1755, from impregnable + -ity.ETD impregnability (n.).2
"one who organizes public entertainments," 1746, from Italian impresario "operatic manager," literally "undertaker (of a business)," from impresa "undertaking, enterprise, attempt," fem. of impreso, past participle of imprendere "undertake," from Vulgar Latin *imprendere, from assimilated form of Latin in- "into, in, on, onto" (from PIE root *en "in") + Latin prehendere "to grasp" (from prae- "before;" see pre-, + -hendere, from PIE root *ghend- "to seize, take").ETD impresario (n.).2
"inalienable, not subject to law or convention," 1560s, from French imprescriptible (16c.) or a native formation from assimilated form of in- (1) "not, opposite of" + Latin praescriptus, past participle of praescribere "to write beforehand, determine in advance, ordain, dictate" (see prescribe). Usually with right (n.). Related: Imperscriptibility. Alternative imprescribable is attested from 1887.ETD imprescriptible (adj.).2
1796, "act of impressing into public service or use," from impress (v.2) + -ment.ETD impressment (n.).2
"capable of receiving impression," 1620s, from impress (v.1) + -able. Related: Impressibly; impressibility.ETD impressible (adj.).2
1590s, "capable of being easily impressed" (a sense now rare or obsolete), from impress (v.1) + -ive. Meaning "capable of making an impression on the mind or senses, tending to excite attention and feeling" is from 1775. Related: Impressively; impressiveness.ETD impressive (adj.).2
"liable to be impressed into public service," 1865, from impress (v.2) + -able. Earlier it was used in the sense "capable of receiving impression" and "impressionable." Related: Impressability.ETD impressable (adj.).2
late 14c., "have a strong effect on the mind or heart, to stamp deeply in the mind," from Latin impressus, past participle of imprimere "press into or upon, stamp," also figurative, from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike"). Literal sense of "to apply with pressure, make a permanent image in, indent, imprint" is from early 15c. in English. Related: Impressed; impressing.ETD impress (v.1).2
early 15c., "pressed or forced upon" (the mind), past-participle adjective from impress (v.).ETD impressed (adj.).2
late 14c., "mark produced by pressure," also "image produced in the mind or emotions by something external," from Old French impression "print, stamp; a pressing on the mind" (13c.), from Latin impressionem (nominative impressio) "a pressing into, onset, attack," figuratively "a perception, mental impression," literally "a pressing into," from imprimere "press into or upon" (see impress (v.1)).ETD impression (n.).2
Meaning "act or process of making a mark upon the surface by pressing" is from early 15c.. Meaning "copy made by pressure from type or an engraving" is from 1550s; that of "printing of a number of copies, aggregate of copies printed at one time" is from 1570s. Meaning "belief, vague notion" (as in under the impression) is from 1610s.ETD impression (n.).3
"act of impressing" (1590s), also "characteristic mark" (1580s), from impress (v.1). From 1620s as "badge worn by nobility or their retainers," from Italian impresa; earlier in English in this sense as impreso, imprese (1580s).ETD impress (n.).2
"levy for military service," 1590s, from assimilated form of in- (2) "into, in" + press (v.2). Related: Impressed; impressing.ETD impress (v.2).2
1839 as a term in philosophy, from impression + -ism. With reference to the French art movement, 1879, from impressionist. Extended 1880s to music (Debussy), literature, etc.ETD impressionism (n.).2
"susceptible to (mental) impressions," 1827, from French impressionable (earliest English examples are in French translations and settings); see impression + -able. Related: Impressionability (1831). Earlier was impressible (1620s).ETD impressionable (adj.).2
in reference to a style of painting aiming to represent overall impressions as they first strike the eye rather than exact details, 1876 (adjective and noun), from French, coined 1874 by French critic Louis Leroy ("école impressionniste") in a disparaging reference to Monet's sunset painting "Impression, Soleil Levant." Later extended to other arts.ETD impressionist (adj., n.).2
"of or pertaining to impressionists or their work," 1883; see impressionist + -ic.ETD impressionistic (adj.).2
"that cannot be foreseen," 1855, from assimilated form of in- "not, opposite of" (see in- (1)) + previsible (see pre- + visible). Related: Imprevision; imprevisibility.ETD imprevisible (adj.).2
"licence to print, granted by a licenser of the press," 1640, Modern Latin, literally "let it be printed," the formula of a book licenser, third person singular present subjunctive passive of Latin imprimere "to print, engrave, stamp; press upon, press against," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike"). Originally of state licence to print books, later only of Roman Catholic Church.ETD imprimatur (n.).2
formerly also emprint, late 14c., imprenten, emprenten, "to mark by pressure, stamp; to impress on the mind or memory," from Old French empreinter "to stamp, engrave, imprint," from empreinte "mark, impression, imprint" (13c.), noun use of fem. past participle of eimpreindre "to impress, imprint," from Vulgar Latin *impremere, from Latin imprimere "to impress, imprint," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike").ETD imprint (v.).2
mid-15c., emprente "an imprint or mark, impression made by printing or stamping," from Old French empreinte "mark, impression, imprint" (see imprint (v.)). Meaning "publication information of a book" (1790) is directly from the verb.ETD imprint (n.).2
c. 1300, from Old French emprisoner "imprison; be in prison" (12c.), from assimilated form of in- "in" (from PIE root *en "in") + prison (see prison). Formerly also emprison. Related: Imprisoned; imprisoning.ETD imprison (v.).2
late 14c., from Anglo-French emprisonement (13c.), Old French emprisonnement "capture, imprisonment" (13c.), from emprisoner (see imprison).ETD imprisonment (n.).2
"want of integrity," 1590s, from Latin improbitas "badness, dishonesty," from assimilated form of in- "not" (see in- (1)) + probitas "uprightness, honesty," from probus "worthy, good" (see prove).ETD improbity (n.).2
1590s, from assimilated form of in- (1) "not, opposite of" + probable, or else from Latin improbabilis. Related: Improbably.ETD improbable (adj.).2
1590s, "fact or quality of being improbable;" see improbable + -ity. Meaning "an instance of something improbable" is from 1610s.ETD improbability (n.).2
"not ready, unprepared," 1759, from Latin impromptus "unready, hesitating," from assimilated form of in- "not, opposite of" (see in- (1)) + promptus "ready" (see prompt (v.)).ETD imprompt (adj.).2
1848, probably from French impromptitude, from assimilated form of in- "not, opposite of" (see in- (1)) + promptitude (see prompt (adj.)).ETD impromptitude (n.).2
1660s, from French impromptu (1650s), from Latin in promptu "in readiness," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + promptu, ablative of promptus "ready, prepared; set forth, brought forward," from past participle of promere "to bring out," from pro "before, forward, for" (see pro-) + emere "obtain" (from PIE root *em- "to take, distribute"). From 1764 as an adjective; as a noun from 1680s.ETD impromptu (adv.).2
mid-15c., "not true," from Old French impropre (14c.) and directly from Latin improprius "not proper," from assimilated form of in- "not, opposite of" (see in- (1)) + proprius (see proper). Meaning "not suited, unfit" is from 1560s; that of "not in accordance with good manners, modesty, or decency" is from 1739. Related: Improperly (late 14c.).ETD improper (adj.).2
1610s, "quality or fact of being improper," from French impropriété (16c.) or directly from Latin improprietas "impropriety," from improprius "improper" (see improper). As "improper thing," 1670s.ETD impropriety (n.).2
1640s, from improve (v.) + -able.ETD improvable (adj.).2
1970 as colloquial shortening for improvisation. The famous New York City comedy club, founded in 1963, was, in full, The Improvisation.ETD improv (n.).2
late 15c., "to use to one's profit, to increase (income)," from Anglo-French emprouwer "to turn to profit" (late 13c.), from Old French en-, a causative prefix or from em-, + prou "profit," from Latin prode "advantageous" (see proud (adj.)).ETD improve (v.).2
Spelling with -v- was rare before 17c.; it apparently arose from confusion of -v- and -u-. Spelling otherwise deformed by influence of words in -prove. Meaning "make better, raise to a better quality or condition" first recorded 1610s. Intransitive sense "get better" is from 1727. Phrase improve the occasion retains the etymological sense. Meaning "to turn land to profit" (by clearing it, erecting buildings, etc.) was in Anglo-French (13c.) and survived or was revived in the American colonies and Australia. Hence, "make good use of, occupy (a place) and convert to some purpose."ETD improve (v.).3