immunodeficiency (n.) Look up immunodeficiency at Dictionary.com
1969, from comb. form of immune + deficiency.
immunology (n.) Look up immunology at Dictionary.com
by 1906, a hybrid from immune + -ology. Related: Immunological; immunologist.
immure (v.) Look up immure at Dictionary.com
1580s, "enclose with walls, shut up, confine," from Middle French emmurer and directly from Medieval Latin immurare, literally "to shut up within walls," from assimilated form of in- "into, in" (see in- (2)) + Latin murus "wall" (see mural). Military sense of "fortify" is from 1590s. Related: Immured; immuring; immurement.
immutability (n.) Look up immutability at Dictionary.com
1590s, from Latin immutabilitas "unchangeableness," from immutabilis "unchangeable" (see immutable).
Nought may endure but Mutability. [Shelley]
immutable (adj.) Look up immutable at Dictionary.com
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" (see mutable). Related: Immutably.
imp (n.) Look up imp at Dictionary.com
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 plant" (see physic). 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.
Suche appereth as aungelles, but in very dede they be ymps of serpentes. [Wynkyn de Worde, "The Pilgrimage of Perfection," 1526]
impact (v.) Look up impact at Dictionary.com
c. 1600, "press closely into something," from Latin impactus, past participle of impingere "to push into, dash against, thrust at" (see impinge). 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.) Look up impact at Dictionary.com
1738, "collision, act of striking against, striking of one thing against another," from impact (v.). Figurative sense of "forceful impression" is from 1817 (Coleridge).
impacted (adj.) Look up impacted at Dictionary.com
1680s, "pressed closely in," past-participle adjective from impact (v.). Of teeth from 1859.
impactful (adj.) Look up impactful at Dictionary.com
1961, originally in advertising, from impact (n.) + -ful. Related: Impactfully; impactfulness.
impaction (n.) Look up impaction at Dictionary.com
1739, from Latin impactionem (nominative impactio) "a striking against," noun of action from past participle stem of impingere "drive into, strike against" (see impinge).
impair (v.) Look up impair at Dictionary.com
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" (see in- (2)) + Late Latin peiorare "make worse" (see pejorative). In reference to driving under the influence of alcohol, first recorded 1951 in Canadian English. Related: Impaired; impairing.
impairment (n.) Look up impairment at Dictionary.com
mid-14c., emparement, from Old French empeirement, from empeirier (see impair). Re-Latinized spelling is from 1610s.
impala (n.) Look up impala at Dictionary.com
1875, from Zulu im-pala "gazelle."
impale (v.) Look up impale at Dictionary.com
1520s, "to enclose with stakes, fence in" (a sense continued in specialized uses into 19c.), from Middle French empaler or directly from Medieval Latin impalare "to push onto a stake," from assimilated form of in- "into, in" (see in- (2)) + Latin palus "a stake, prop, stay; wooden post, pole," from PIE *pak-slo-, from root *pag-/*pak- "to fasten" (see pact). Sense of "pierce with a pointed stake" (as torture or capital punishment) first recorded 1610s. Related: Impaled; impaling.
impalement (n.) Look up impalement at Dictionary.com
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.
impalpable (adj.) Look up impalpable at Dictionary.com
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.) Look up impanate at Dictionary.com
"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" (see in- (2)) + panis "bread," from PIE root *pa- "to feed" (see food). Related: Impanation (1540s), from Medieval Latin impanationem.
impanel (v.) Look up impanel at Dictionary.com
"to fit with panels," 1570s; see im- "in" + panel (n.). Related: Impanelled. Also empanel.
imparity (n.) Look up imparity at Dictionary.com
1560s, from Late Latin imperitas, from assimilated form of in- "not, opposite of" (see in- (1)) + paritas "equality" (see parity). Rare or obsolete.
impart (v.) Look up impart at Dictionary.com
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" (see in- (2)) + partire "to divide, part" (see part (v.)). 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.
impartial (adj.) Look up impartial at Dictionary.com
"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.
impartiality (n.) Look up impartiality at Dictionary.com
"fairness, freedom from bias," 1610s; see impartial + -ity.
impartible (adj.) Look up impartible at Dictionary.com
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.
impassable (adj.) Look up impassable at Dictionary.com
"that cannot be passed or passed over," 1560s, from assimilated form of in- (1) "not, opposite of" + passable. Related: Impassability.
impasse (n.) Look up impasse at Dictionary.com
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.
... dans l'impasse de St Thomas du Louvre; car j'appelle impasse, Messieurs, ce que vous appelez cul-de-sac: je trouve qu'une rue ne ressemble ni à un cul ni à un sac: je vous prie de vous servir du mot d'impasse, qui est noble, sonore, intelligible, nécessaire, au lieu de celui de cul, ... (etc.) [Voltaire, "A Messieurs Les Parisiens"]
impassible (adj.) Look up impassible at Dictionary.com
"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.
impassion (v.) Look up impassion at Dictionary.com
1590s, "inflame with passion," from Italian impassionare "to fill with passion," from assimilated form of in- "in, into" (see in- (2)) + passione "passion," from Latin passionem (see passion). Related: Impassioned; impassionable. Formerly also empassion.
impassionate (adj.) Look up impassionate at Dictionary.com
"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).
impassioned (adj.) Look up impassioned at Dictionary.com
"expressive of strong feeling, filled with passion," c. 1600, past participle adjective from impassion.
impassive (adj.) Look up impassive at Dictionary.com
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).
impassivity (n.) Look up impassivity at Dictionary.com
1789, from impassive + -ity. Earlier in the same sense was impassiveness (1640s).
impasto (n.) Look up impasto at Dictionary.com
"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" (see in- (2)) + pasta "paste" (see pasta). Nativized form impaste is attested from 1540s as "enclose in paste," 1727 in reference to painting. Related: Impastoed; impastation.
impatience (n.) Look up impatience at Dictionary.com
"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.) Look up impatiens at Dictionary.com
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.
impatient (adj.) Look up impatient at Dictionary.com
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.
impeach (v.) Look up impeach at Dictionary.com
formerly also empeach, late 14c., "to impede, hinder, prevent," 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" (see in- (2)) + Latin pedica "a shackle, fetter," from pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)). Sense of "accuse a public officer of misconduct" first recorded 1560s, perhaps via Medieval Latin confusion of the word with Latin impetere "attack, accuse" (see impetus). Related: Impeached; impeaching.
impeachable (adj.) Look up impeachable at Dictionary.com
c. 1500, from impeach + -able. Related: impeachably; impeachability.
impeachment (n.) Look up impeachment at Dictionary.com
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.
impeccable (adj.) Look up impeccable at Dictionary.com
1530s, "not capable of sin," from Middle 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.) Look up impecunious at Dictionary.com
"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.
impedance (n.) Look up impedance at Dictionary.com
"hindrance," especially and originally "resistance due to induction in an electrical circuit," 1886, from impede + -ance. The classically correct formation would be *impedience.
impede (v.) Look up impede at Dictionary.com
c. 1600, back-formation from impediment, or else from Latin impedire "impede, be in the way, hinder, detain," literally "to shackle the feet." Related: Impeded; impedes; impeding; impedient.
impediment (n.) Look up impediment at Dictionary.com
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" (see in- (2)) + pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)). Related: Impedimental.
impedimenta (n.) Look up impedimenta at Dictionary.com
"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).
impel (v.) Look up impel at Dictionary.com
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" (see in- (2)) + pellere "to push, drive" (see pulse (n.1)). Related: Impelled; impelling.
impeller (n.) Look up impeller at Dictionary.com
1680s, agent noun from impel (v.). As a machine part from 1836.
impend (v.) Look up impend at Dictionary.com
"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" (see in- (2)) + pendere "hang" (see pendant). Literal sense in English is by 1780. Related: Impended; impending.
impendent (adj.) Look up impendent at Dictionary.com
1590s, from Latin impendentem (nominative impendens) "impending," present participle of impendere "to hang over" (see impend). Related: Impendence.
impenetrable (adj.) Look up impenetrable at Dictionary.com
mid-15c., from Middle 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.