Etymology dictionary
immortality (n.) — impetus (n.)
immortality (n.)
mid-14c., "deathlessness," from Old French immortalité (13c.) and directly from Latin immortalitatem (nominative immortalitas) "deathlessness, endless life," also "imperishable fame," from immortalis "undying" (see immortal). Of fame, etc., "quality of being permanent," early 15c.
immortal (adj.)
late 14c., "deathless," from Latin immortalis "deathless, undying" (of gods), "imperishable, endless" (of fame, love, work, etc.), from assimilated form of in- "not, opposite of" (see in- (1)) + mortalis "mortal" (from PIE root *mer- "to rub away, harm," also "to die" and forming words referring to death and to beings subject to death). In reference to fame, literature, etc., "unceasing, destined to endure forever, never to be forgotten, lasting a long time," attested from early 15c. (also in classical Latin). As a noun, "an immortal being," from 1680s.
immortalise (v.)
chiefly British English spelling of immortalize (q.v.); for suffix, see -ize. Related: immortalisation; immortalised; immortalising.
immortelle (n.)
"flower which preserves its shape and color after being dried" (also known as an everlasting), 1832, from French fem. of immortel "undying," from Latin immortalis (see immortal).
immovable (adj.)
late 14c., literal and figurative, also sometimes in Middle English immevable, from assimilated form of in- (1) "not, opposite of" + movable. Related: Immovably.
immovability (n.)
late 14c., immoevablete, "quality of being unchanging," from immovable + -ity.
immunity (n.)
late 14c., "exemption from service or obligation," from Old French immunité "privilege; immunity from attack, inviolability" (14c.) and directly from Latin immunitatem (nominative immunitas) "exemption from performing public service or charge, privilege," from immunis "exempt, free, not paying a share" (see immune (adj.)). Medical sense of "protection from disease" is from 1879, from French or German.
immunize (v.)
1889, in a translation of a German article, from immune + -ize. Related: Immunized; immunizing.
immunization (n.)
1892, noun of action from immunize.
immune (adj.)
mid-15c., "free, exempt" (from taxes, tithes, sin, etc.), from Latin immunis "exempt from public service, untaxed; unburdened, not tributary," literally "not paying a share," from assimilated form of in- "not, opposite of" (see in- (1)) + munis "performing services" (compare municipal), from PIE *moi-n-es-, suffixed form of root *mei- (1) "to change, go, move." Specific modern medical sense of "exempt (from a disease)," typically because of inoculation, is from 1881, a back-formation from immunity. Immune system attested by 1917.
immunodeficiency (n.)
1969, from combining form of immune + deficiency.
immunology (n.)
by 1906, a hybrid from immune + -ology. Related: Immunological; immunologist.
immure (v.)
1580s, "enclose with walls, shut up, confine," from French emmurer and directly from Medieval Latin immurare, literally "to shut up within walls," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin murus "wall" (see mural). Military sense of "fortify" is from 1590s. Related: Immured; immuring; immurement.
immutability (n.)
1590s, from Latin immutabilitas "unchangeableness," from immutabilis "unchangeable" (see immutable).
immutable (adj.)
early 15c., "unchanging, unalterable," from Old French immutable (Modern French immuable), and directly from Latin immutabilis "unchangeable, unalterable," from assimilated form of in- "not, opposite of" (see in- (1)) + mutabilis "changeable," from mutare "to change" (from PIE root *mei- (1) "to change, go, move"). Related: Immutably.
imp (n.)
Old English impe, impa "young shoot, graft," from impian "to graft," probably an early Germanic borrowing from Vulgar Latin *imptus, from Late Latin impotus "implanted," from Greek emphytos, verbal adjective formed from emphyein "implant," from em- "in" + phyein "to bring forth, make grow," from PIE root *bheue- "to be, exist, grow." Compare Swedish ymp, Danish ympe "graft."
The sense of the word has shifted from plants to people, via the meaning "child, offspring" (late 14c., now obsolete), from the notion of "newness." The current meaning "little devil" is attested from 1580s, from common pejorative phrases such as imp of Satan. The extension from this to "mischievous or pert child" (1640s) unconsciously turns the word back toward its Middle English sense.
impacted (adj.)
1680s, "pressed closely in," past-participle adjective from impact (v.). Of teeth from 1859.
impact (v.)
c. 1600, "press closely into something," from Latin impactus, past participle of impingere "to push into, 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"). Original sense is preserved in impacted teeth. Sense of "strike forcefully against something" first recorded 1916. Figurative sense of "have a forceful effect on" is from 1935. Related: Impacting.
impact (n.)
1738, "collision, act of striking against, striking of one thing against another," from impact (v.). Figurative sense of "forceful impression" is from 1817 (Coleridge).
impaction (n.)
1739, from Latin impactionem (nominative impactio) "a striking against," noun of action from past participle stem of impingere "drive into, strike against" (see impinge).
impactful (adj.)
1959, in psychotherapy, from impact (n.) + -ful. Related: Impactfully; impactfulness.
impairment (n.)
mid-14c., emparement, from Old French empeirement, from empeirier (see impair). Re-Latinized spelling is from 1610s.
impair (v.)
late 14c., a re-Latinizing of earlier ampayre, apeyre "make worse, cause to deteriorate" (c. 1300), from Old French empeirier "make worse" (Modern French empirer), from Vulgar Latin *impeiorare "make worse," from assimilated form of in- "into, in" (from PIE root *en "in") + Late Latin peiorare "make worse," from peior "worse," perhaps originally "stumbling," from PIE *ped-yos-, suffixed (comparative) of *ped- "to walk, stumble, impair," from root *ped- "foot. In reference to driving under the influence of alcohol, first recorded 1951 in Canadian English. Related: Impaired; impairing.
impale (v.)
1520s, "to enclose with stakes, fence in" (a sense continued in specialized uses into 19c.), from French empaler or directly from Medieval Latin impalare "to push onto a stake," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin palus "a stake, prop, stay; wooden post, pole" (from PIE *pak-slo-, from root *pag- "to fasten"). Sense of "pierce with a pointed stake" (as torture or capital punishment) first recorded 1610s. Related: Impaled; impaling.
impalement (n.)
1590s, "act of enclosing with stakes," from impale (v.) + -ment, perhaps on model of French empalement; formerly in English it often was spelled empalement. In reference to the method of torture/punishment from 1620s.
impala (n.)
1875, from Zulu im-pala "gazelle."
impalpable (adj.)
c. 1500, "too unsubstantial to be perceived by touch," from French impalpable or directly from Medieval Latin impalpabilis, from assimilated form of in- "not, opposite of" (see in- (1)) + palpabilis (see palpable). Figurative (mental) sense of "that cannot be grasped by the intellect" is from 1774. Related: Impalpably; impalpability.
impanate (adj.)
"present in the (consecrated) bread," 1540s, from Church Latin impanatus, past participle of impanare "to embody in bread," from assmiliated form of in- "in, into" (from PIE root *en "in") + panis "bread" (from PIE root *pa- "to feed").
Related: Impanation (1540s), from Medieval Latin impanationem. The Adessenarians (1751, from Latin adesse "be present," from ad- "to" + esse "be") believed in the real presence of Christ's body in the eucharist, not by transubstantiation but by impanation. Subpanation, meanwhile, is the view that Christ "is under the form of bread and wine in a localized or materialistic sense" [Century Dictionary].
impanel (v.)
"to fit with panels," 1570s; see im- "in" + panel (n.). Related: Impanelled. Also empanel.
imparity (n.)
1560s, from Late Latin imperitas, from assimilated form of in- "not, opposite of" (see in- (1)) + paritas "equality," from Latin adjective par (genitive paris) "equal" (see par). Rare or obsolete.
impart (v.)
early 15c., "to give a part of (one's possessions);" late 15c., "to share, take part in," from Old French empartir, impartir "assign, allot, allocate, share out" (14c.), from Late Latin impartire (also impertire) "to share in, divide with another; communicate," from assimilated form of in- "into, in" (from PIE root *en "in") + partire "to divide, part" (from pars "a part, piece, a share," from PIE root *pere- (2) "to grant, allot").
Meaning "communicate as knowledge or information" is from 1540s; the word was not originally restricted to immaterial things but now usually is only in reference to qualities. Related: Imparted; imparting; impartment.
impartible (adj.)
late 14c. as "indivisible, incapable of being parted," from Medieval Latin impartibilis; see im- "not, opposite of" + part (v.). From 1630s as "capable of being imparted," from impart (v.) + -ible. Now little used in either sense.
impartiality (n.)
"fairness, freedom from bias," 1610s; see impartial + -ity.
impartial (adj.)
"not partial, not favoring one over another," 1590s, from assimilated form of in- (1) "not, opposite of" + partial. First recorded use is in "Richard II." Related: Impartially.
impasse (n.)
1763, "blind alley, dead end," from French impasse "impassable road; blind alley; impasse" (18c.), from assimilated form of in- "not, opposite of" (see in- (1)) + passe "a passing," from passer "to pass" (see pass (v.)). Figurative use (c. 1840) is perhaps from its use in whist. Supposedly coined by Voltaire as a euphemism for cul de sac.
impassible (adj.)
"incapable of feeling pain, exempt from suffering," mid-14c., from Old French impassible (13c.) or directly from Church Latin impassibilis "incapable of passion," from assimilated form of in- "not, opposite of" (see in- (1)) + passibilis "capable of passion, feeling, or suffering, from passio "suffering" (see passion). Meaning "emotionless" is from 1590s. Related: Impassibility.
impassivity (n.)
1789, from impassive + -ity. Earlier in the same sense was impassiveness (1640s).
impassive (adj.)
1660s, "not feeling pain, insen" from assimilated form of in- "not, opposite of" (see in- (1)) + passive. Meaning "void of emotions, unmoved" is from 1690s. Related: Impassively; impassiveness (1640s).
impassion (v.)
1590s, "inflame with passion," from Italian impassionare "to fill with passion," from assimilated form of in- "in, into" (from PIE root *en "in") + passione "passion," from Latin passionem (see passion). Related: Impassioned; impassionable. Formerly also empassion.
impassable (adj.)
"that cannot be passed or passed over," 1560s, from assimilated form of in- (1) "not, opposite of" + passable. Related: Impassability.
impassioned (adj.)
"expressive of strong feeling, filled with passion," c. 1600, past-participle adjective from impassion.
impassionate (adj.)
"free from passion, dispassionate," 1620s, from in- (1) "not" + passionate. Related: Impassionately. From 1590s as "strongly affected, stirred by passion," from Italian impassionato, past participle of impassionare (see impassion).
impasto (n.)
"laying on of colors thickly and boldly," 1784, from Italian impasto, noun of action from impastare "to raise paste; to put in paste," from assimilated form of in- "into, in" (from PIE root *en "in") + pasta "paste" (see pasta). Nativized form impaste is attested from 1540s as "enclose in paste," 1727 in reference to painting. Related: Impastoed; impastation.
impatient (adj.)
late 14c., from Old French impacient "impatient" (Modern French impatient), from Latin impatientem (nominative impatiens) "that cannot bear, intolerant, impatient," from assimilated form of in- "not, opposite of" (see in- (1)) + patiens "bearing, enduring" (see patience). Related: Impatiently.
impatience (n.)
"restlessness under existing conditions," c. 1200, from Old French impacience "impatience" (12c., Modern French impatience) and directly from Latin impatientia "impatience; weakness," from impatiens "intolerant, impatient" (see impatient).
impatiens (n.)
type of flowering plant, from Latin impatiens "impatient" (see impatient). So called in reference to the valves of the seed pods, which discharge forcibly at a slight touch.
impeachment (n.)
late 14c., enpechement "accusation, charge," from Old French empeechement "difficulty, hindrance; (legal) impeachment," from empeechier "to hinder, impede" (see impeach). As a judicial proceeding on charges of maladministration against a public official, from 1640s.
impeach (v.)
formerly also empeach, late 14c., empechen, "to impede, hinder, prevent;" early 15c., "cause to be stuck, run (a ship) aground," also "prevent (from doing something)," from Anglo-French empecher, Old French empeechier "to hinder, stop, impede; capture, trap, ensnare" (12c., Modern French empêcher), from Late Latin impedicare "to fetter, catch, entangle," from assimilated form of in- "into, in" (from PIE root *en "in") + Latin pedica "a shackle, fetter," from pes (genitive pedis) "foot" (from PIE root *ped- "foot").
In law, at first in a broad sense, "to accuse, bring charges against" from late 14c.; more specifically, of the king or the House of Commons, "to bring formal accusation of treason or other high crime against (someone)" from mid-15c. The sense of "accuse a public officer of misconduct" had emerged from this by 1560s. The sense shift is perhaps via Medieval Latin confusion of impedicare with Latin impetere "attack, accuse" (see impetus), which is from the Latin verb petere "aim for, rush at" (from PIE root *pet- "to rush, to fly").
The Middle English verb apechen, probably from an Anglo-French variant of the source of impeach, was used from early 14c. in the sense "to accuse (someone), to charge (someone with an offense)." Related: Impeached; impeaching.
impeachable (adj.)
early 15c., empechable, "liable to impeachment," from Old French; see impeach + -able. Related: impeachably; impeachability.
impeccable (adj.)
1530s, "not capable of sin," from French impeccable (15c.) or directly from Late Latin impeccabilis "not liable to sin," from assimilated form of in- "not, opposite of" (see in- (1)) + peccare "to sin" (see peccadillo). Meaning "faultless" is from 1610s. Related: Impeccably; impeccant; impeccancy.
impecunious (adj.)
"lacking in money," 1590s, from assimilated form of in- "not, opposite of" (see in- (1)) + Latin pecuniosus "rich," from pecunia "money, property" (see pecuniary). Related: Impecuniously; impecuniosity.
impede (v.)
c. 1600, back-formation from impediment, or else from Latin impedire "impede, be in the way, hinder, detain," literally "to shackle the feet," from assimilated form of in- "into, in" (from PIE root *en "in") + pes (genitive pedis) "foot," from PIE root *ped- "foot." Related: Impeded; impedes; impeding; impedient.
impedance (n.)
"hindrance," especially and originally "resistance due to induction in an electrical circuit," 1886, from impede + -ance. The classically correct formation would be *impedience.
impediment (n.)
c. 1400, from Old French empedement or directly from Latin impedimentum "hindrance," from impedire "impede," literally "to shackle the feet," from assimilated form of in- "into, in" (from PIE root *en "in") + pes (genitive pedis) "foot," from PIE root *ped- "foot." Related: Impedimental.
impedimenta (n.)
"traveling equipment," c. 1600, from Latin impedimenta "luggage, military baggage," literally "hindrances," on the notion of "that by which one is impeded;" plural of impedimentum "hindrance" (see impediment).
impeller (n.)
1680s, agent noun from impel (v.). As a machine part from 1836.
impel (v.)
early 15c., from Latin impellere "to push, strike against; set in motion, drive forward, urge on," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pellere "to push, drive" (from PIE root *pel- (5) "to thrust, strike, drive"). Related: Impelled; impelling.
impend (v.)
"be about to happen" (usually of something unwanted), 1590s, from Latin impendere "to hang over;" figuratively "to be imminent, be near," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + pendere "to hang" (from PIE root *(s)pen- "to draw, stretch, spin"). Literal sense in English is by 1780. Related: Impended; impending.
impendent (adj.)
1590s, from Latin impendentem (nominative impendens) "impending," present participle of impendere "to hang over" (see impend). Related: Impendence.
impenetrable (adj.)
"impossible to penetrate," mid-15c., from Old French impenetrable (14c.) or directly from Latin impenetrabilis "that cannot be penetrated," from assimilated form of in- "not, opposite of" (see in- (1)) + penetrabilis "penetrable" (see penetrable). Related: Impenetrably; impenetrability.
impenitent (adj.)
early 15c., from Latin impaenitentem, from assimilated form of in- "not, opposite of" (see in- (1)) + paenitens (see penitence). As a noun, "hardened sinner," from 1530s.
impenitence (n.)
1620s, from Late Latin impaenitentia, from impaenitens (see impenitent). The older form in English is Impenitency (1560s).
imperative (adj.)
1520s, in grammar, "expressing command," used of the form of a verb which expresses command, entreaty, advice, or exhortation, from Late Latin imperativus "pertaining to a command," from imperat-, past participle stem of imperare "to command, requisition," from assimilated form of in- "into, in" (from PIE root *en "in") + parare "to arrange, prepare, adorn" (from PIE root *pere- (1) "to produce, procure").
imperator (n.)
"absolute ruler," 1580s, from Latin imperator "commander-in-chief, leader, master," agent noun from stem of imperare "to command" (see imperative (adj.)). In the Roman republic, a holder of military command during active service, also a title bestowed on victorious generals; in the Roman Empire, the emperor as commander-in-chief of the armies. Related: Imperatorial.
imperative (n.)
mid-15c., in grammar; later "something imperative" (c. 1600), from Old French imperatif in the grammatical sense (13c.) and directly from Late Latin imperativus (see imperative (adj.)). In philosophy from 1796.
imperceptible (adj.)
early 15c., from Medieval Latin imperceptibilis, from assimilated form of in- "not, opposite of" (see in- (1)) + perceptibilis (see perceptible). Related: Imperceptibly; imperceptibility. OED marks imperceivable (1610s) as "Now rare."
imperception (n.)
"want of perception," 1620s, from assimilated form of in- (1) "not, opposite of" + perception.
imperceptive (adj.)
"not perceiving," 1660s, from assimilated form of in- (1) "not, opposite of" + perceptive.
imperceptibility (n.)
1670s, from imperceptible + -ity.
imperfection (n.)
late 14c., "incompleteness, deficiency, lack," from Old French imperfeccion "defect; imperfect state" (12c.) and directly from Late Latin imperfectionem (nominative imperfectio) "imperfection," noun of action from Latin imperfectus "imperfect"(see imperfect). Meaning "an instance of being imperfect" is from early 15c.
imperfect (adj.)
late 14c., imparfit, "sinful, immoral; not properly formed, not complete, immature; rudimentary, elementary," from Old French imparfait, from Latin imperfectus "unfinished, incomplete, immature," from assimilated form of in- "not, opposite of" (see in- (1)) + perfectus "finished, complete" (see perfect (adj.)). Altered mid-16c. to conform to Latin, along with perfect. Related: Imperfectly.
imperforate (adj.)
"having no perforation," 1670s, from assimilated form of in- (1) "not, opposite of" + perforate (adj.). Related: Imperforation (1650s).
imperialism (n.)
1826, "advocacy of empire, devotion to imperial interests," originally in a Napoleonic context, but also used of Rome and of British foreign policy; from imperial + -ism.
At times in British use (and briefly in U.S.) with a neutral or positive sense relating to national interests or the spread of the benefits of Western civilization, but from the beginning usually more or less a term of reproach.
The general sense of "one country's rule over another" is recorded by 1878. The word's pejorative quality sharpened after 1900, with U.S. revulsion at the Philippine insurrection and the publication of J.A. Hobson's book on imperialism, through which the term was taken up in the 1910s by communist writers.
imperial (adj.)
late 14c., "having a commanding quality," from Old French imperial, emperial "imperial; princely, splendid; strong, powerful" (12c.), from Latin imperialis "of the empire or emperor," from imperium "empire" (see empire).
Meaning "pertaining to an empire" (especially Rome's) is from late 14c.; by 1774 of Britain's. Meaning "of imposing size or excellence" is from 1731. Imperial presidency in a U.S. context traces to Arthur Schlesinger Jr.'s book on the Nixon administration (1974). Related: Imperially. The noun is from 1520s as "member of the emperor's party;" 1670s as the name of gold coins issued by various imperial authorities.
imperious (adj.)
1540s, "of a dominating character," from Latin imperiosus "commanding, mighty, powerful," from imperium "empire, command" (see empire). Formerly also emperious. Meaning "imperial" is from 1580s. Related: Imperiously; imperiousness.
imperialistic (adj.)
1872, from imperialist + -ic.
imperialist (n.)
c. 1600, "an adherent of an emperor or the imperial cause," such as the emperor of Germany (in the Thirty Years' War), France, China, etc., probably modeled on French impérialiste (early 16c.); from imperial + -ist. The shift in meaning to "advocate of imperialism" (1893) came via the British Empire, which involved a worldwide colonial system. See imperialism. As a term of abuse in communist circles, attested by 1918. As an adjective by 1816.
imperil (v.)
1590s, from assimilated form of in- "into, in" (from PIE root *en "in") + peril. Formerly also emperil. Related: Imperiled; imperiling; imperilment.
imperishable (adj.)
"not subject to destruction or decay," 1640s, from assimilated form of in- "not, opposite of" (see in- (1)) + perishable. Related: Imperishably
imperium (n.)
"authority to command the national military forces," in extended use "an empire," 1650s, from Latin imperium "command, supreme authority, power" (see empire). Hence Latin phrase imperium in imperio "a state within a state."
impermeable (adj.)
1690s, from French imperméable or directly from Late Latin impermeabilis, from assimilated form of in- "not, opposite of" (see in- (1)) + permeabilis (see permeable). Related: Impermeability.
impermanent (adj.)
1650s, from assimilated form of in- "not, opposite of" (see in- (1)) + permanent.
impermanence (n.)
1796, from impermanent + -ence. Impermanency is from 1640s.
impermissible (adj.)
1814, from assimilated form of in- "not, opposite of" (see in- (1)) + permissible.
imperscriptible (adj.)
"unrecorded, without written authority," 1792 (used almost exclusively with right (n.)), from French imperscriptible, from assimilated form of Latin in- "not, opposite of" (see in- (1)) + perscribere "to write down." Earliest in English in reference to the French evolution. Spelling imperscriptable attested from 1827.
impersonal (adj.)
mid-15c., a grammatical term, from Late Latin impersonalis, from assimilated form of in- "not, opposite of" (see in- (1)) + personalis "personal" (see personal). Sense of "not connected with any person" is from 1620s; that of "not endowed with personality, having no conscious individuality" is from 1842. Related: impersonally.
impersonator (n.)
1833, "one who embodies the person or character of another;" 1840 as "one who infuses (something) with a personality;" 1842 as "dramatic actor, one who plays a part on stage," from impersonate with Latinate agent noun suffix. Meaning "one who imitates the manners and speech of another" for entertainment (by 1921) perhaps grew from older theatrical use of female impersonator (1876), male impersonator (1874), both once popular stage acts; the first example of the latter was perhaps Miss Ella Wesner, who had a vogue c. 1870: In Britain, blackface performers were called negro impersonators (1906). As a fem. formation, impersonatrix, as if from Latin, is from 1847; impersonatress, as if from French, is from 1881.
impersonation (n.)
1800, "personification;" 1825 as "an acting of a part or character;" noun of action from impersonate (v.).
impersonality (n.)
1769, from impersonal + -ity.
impersonate (v.)
1620s, "represent in bodily form," from assimilated form of Latin in- "into, in" (from PIE root *en "in") + persona "person" (see person (n.)). The sense of "assume the person or character of" is recorded by 1715; earlier in that sense was personate (1610s). Related: Impersonated; impersonating.
impersuadable (adj.)
1763, from assimilated form of in- (1) "not, opposite of" + persuadable. [Earliest date in OED 2nd ed. print is a typo.]
impersuasible (adj.)
1570s, from assimilated form of in- (1) "not, opposite of" + persuasible (see persuadable).
impertinent (adj.)
late 14c., "unconnected, unrelated, not to the point" (now obsolete; OED's last citation is from Coleridge), from Old French impertinent (14c.) or directly from Late Latin impertinentem (nominative impertinens) "not belonging," literally "not to the point," from assimilated form of Latin in- "not, opposite of" (see in- (1)) + pertinens (see pertinent). Sense of "rudely bold, uncivil, offensively presumptuous" is from 1680s, from earlier sense of "not appropriate to the situation" (1580s), which probably is modeled on similar use in French, especially by Molière, from notion of meddling in what is beyond one's proper sphere.
impertinence (n.)
c. 1600, "incivility," from French impertinence, from impertinent (see impertinent). Meaning "irrelevance" is from 1620s. Impertinency is from 1580s as "a triviality, an absurdity."
impertinently (adv.)
mid-15c., "not to the point, irrelevantly," from impertinent + -ly (2). Meaning "intrusively, presumptuously" is from 1640s.
imperturbable (adj.)
c. 1500, from French imperturbable (15c.) and directly from Late Latin imperturbabilis "that cannot be disturbed" (Augustine), from assimilated form of in- "not, opposite of" (see in- (1)) + *perturbabilis, from Latin perturbare "to confuse, disturb" (see perturb). Related: Imperturbably (1785); imperturbability (1831; earlier as a dictionary word); imperturbation.
imperturbed (adj.)
1721, from assimilated form of in- (1) "not" + perturbed. Related: Imperturbedly.
impervious (adj.)
1640s, from Latin impervius "not to be traverse, that cannot be passed through, impassible," from assimilated form of in- "not, opposite of" (see in- (1)) + pervius "letting things through, that can be passed through," from per "through" (from PIE root *per- (1) "forward," hence "through") + via "road" (see via (adv.)). Related: Imperviously; imperviousness.
impetigo (n.)
pustular disease of the skin, late 14c., from Latin impetigo "skin eruption," from impetere "to attack" (see impetus). Originally used generally; the sense narrowed in modern times to specific diseases. Related: Impetiginous.
impetuous (adj.)
late 14c., "hot-tempered, fierce;" late 15c., "done or given with a rush of force," from Old French impetuos (13c., Modern French impétueux) and directly from Late Latin impetuosus "impetuous, violent" (source also of Spanish and Italian impetuoso), from Latin impetus "attack" (see impetus). Related: Impetuously; impetuousness.
impetus (n.)
early 15c., impetous "rapid movement, rush;" 1640s, with modern spelling, "force with which a body moves, driving force," from Latin impetus "an attack, assault; rapid motion; an impulse; violence, vigor, force;" figuratively "ardor, passion," from impetere "to attack," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + petere "aim for, rush at" (from PIE root *pet- "to rush, to fly").