defeat (v.) Look up defeat at
late 14c., from Anglo-French defeter, from Old French desfait, past participle of desfaire "to undo," from Vulgar Latin *diffacere "undo, destroy," from Latin dis- "un-, not" (see dis-) + facere "to do, perform" (see factitious). Original sense was of "bring ruination, cause destruction." Military sense of "conquer" is c. 1600. Related: Defeated; defeating.
defeat (n.) Look up defeat at
1590s, from defeat (v.).
defeatism (n.) Look up defeatism at
1918; see defeatist.
defeatist Look up defeatist at
1918, adjective and noun, in reference to pacifists and political opposition in Britain, from French défaitiste, which was used there in reference to the Russians who sought to end their war with Germany; see defeat (n.) + -ist. Their opposition, in the original Russian context, were called defensists.
defecate (v.) Look up defecate at
1570s, "to purify," from Latin defaecatus, past participle of defaecare "cleanse from dregs, purify," from the phrase de faece "from dregs" (plural faeces; see feces). Excretory sense first recorded 1830 (defecation), American English, from French. Related: Defecated; defecating.
defecation (n.) Look up defecation at
1620s, from Late Latin defecationem (nominative deficatio), noun of action from past participle stem of Latin defecare (see defecate). An Old English word for "bowel movement" was arse-gang literally "arse-going."
defect (n.) Look up defect at
early 15c., from Middle French defect and directly from Latin defectus "failure, revolt, falling away," noun use of past participle of deficere "to fail, desert" (see deficient).
defect (v.) Look up defect at
1570s, from Latin defectus, past participle of deficere "to fail, desert" (see defect (n.)). Related: Defected; defecting.
defection (n.) Look up defection at
1540s, "action of failing;" 1550s, "action of deserting a party, leader, etc." from Latin defectionem (nominative defectio) "desertion, revolt, failure," noun of action from past participle stem of deficere (see deficient). Originally used often of faith.
defective (adj.) Look up defective at
mid-14c., from Middle French défectif (14c.) and directly from Late Latin defectivus, from defect-, past participle stem of deficere (see deficient). A euphemism for "mentally ill" from 1898 to c. 1935. Related: Defectively; defectiveness.
defector (n.) Look up defector at
1660s, agent noun in Latin form from defect, or else from Latin defector "revolter," agent noun from deficere (see deficient).
defence Look up defence at
see defense.
defend (v.) Look up defend at
mid-13c., from Old French defendre (12c.) "defend, resist," and directly from Latin defendere "ward off, protect, guard, allege in defense," from de- "from, away" (see de-) + -fendere "to strike, push," from PIE root *gwhen- "to strike, kill" (see bane). In the Mercian hymns, Latin defendet is glossed by Old English gescildeð. Related: Defended; defending.
defendant (n.) Look up defendant at
c. 1400, in the legal sense, from French défendant, present participle of défendre (see defend). Earliest use in English was as a present participle adjective meaning "defending" (c. 1300).
defender (n.) Look up defender at
c. 1300 (early 13c. as a surname), via Anglo-French, from Old French defendeor, agent noun from defendre (see defend). The Latin word in this sense was defensor.
defenestration (n.) Look up defenestration at
1620, "the action of throwing out of a window," from Latin fenestra "window" (see fenestration). A word invented for one incident: the "Defenestration of Prague," May 21, 1618, when two Catholic deputies to the Bohemian national assembly and a secretary were tossed out the window (they landed in a trash heap and survived) of the castle of Hradschin by Protestant radicals. It marked the start of the Thirty Years War.
The extraordinary chance which had saved three lives was a holy miracle or a comic accident according to the religion of the beholder .... Murder or no murder, the coup d'état was complete, and since Thurn had overruled many of his supporters in demanding death it was well for the conscience of his allies that a pile of mouldering filth in the courtyard of the Hradschin had made soft falling for the governors. [Cicely Veronica Wedgwood, "The Thirty Years War," 1938]
Some linguists link fenestra with Greek verb phainein "to show;" others see in it an Etruscan borrowing, based on the suffix -(s)tra, as in Latin loan-words aplustre "the carved stern of a ship with its ornaments," genista "the plant broom," lanista "trainer of gladiators." Related: Defenestrate (1915); defenestrated (1620).
defense (n.) Look up defense at
c. 1300, "forbidding, prohibition," also "action of guarding or protecting," from Old French defense, from Latin defensus, past participle of defendere "ward off, protect" (see defend). But it also arrived (without the final -e) from Old French defens, from Latin defensum "thing protected or forbidden," neuter past participle of defendere.

Defens was assimilated into defense, but not before it inspired the alternative spelling defence, via the same tendency that produced hence (hennis), pence (penies), dunce (Duns). First used 1935 as a euphemism for "national military resources." Defense mechanism in psychology is from 1913.
defenseless (adj.) Look up defenseless at
also defenceless, 1520s, from defense + -less. Related: Defenselessly.
defensible (adj.) Look up defensible at
late 13c., from Old French defensable, from Late Latin defensibilem, from Latin defens-, past participle stem of defendere (see defend).
defensive Look up defensive at
c. 1400 (adj. and noun), from French défensif (14c.), from Medieval Latin defensivus, from defens-, past participle stem of Latin defendere (see defend). Of persons, "alert to reject criticism," from 1919. Related: Defensively; defensiveness.
defer (v.1) Look up defer at
"to delay," late 14c., differren, deferren, from Old French differer (14c.), from Latin differre "carry apart, scatter, disperse;" also "be different, differ;" also "defer, put off, postpone," (see differ). Etymologically identical with differ; the spelling and pronunciation differentiated from 15c., perhaps partly by association of this word with delay.
defer (v.2) Look up defer at
"yield," mid-15c., from Middle French déférer (14c.) "to yield, comply," from Latin deferre "carry away, transfer, grant," from de- "down, away" (see de-) + ferre "carry" (see infer). Main modern sense is from meaning "refer (a matter) to someone," which also was in Latin.
deference (n.) Look up deference at
1640s, from French déférence (16c.), from déférer (see defer (v.2)).
deferent (adj.) Look up deferent at
1620s, from French déférent (16c.), from Latin deferentem (nominative deferens), present participle of deferre "to carry down or away" (see defer (v.2)). Earlier in Middle English as a word in astronomy (early 15c.).
deferential (adj.) Look up deferential at
1822, from deferent + -ial; as a word in anatomy, from 1877. Related: Deferentially.
deferment (n.) Look up deferment at
1610s, from defer (v.1) + -ment. As a word for "conditional exemption from a military draft" it dates to 1918, American English.
deferral (n.) Look up deferral at
1895, from defer (v.1) + -al (2).
deferred (adj.) Look up deferred at
"delayed," 1660s, past participle adjective from defer (v.1).
defiance (n.) Look up defiance at
c. 1300, from Old French desfiance "challenge, declaration of war," from desfiant, present participle of desfier (see defy).
defiant (adj.) Look up defiant at
1837, from French défiant, present participle of défier (see defy). Related: Defiantly.
defibrillation (n.) Look up defibrillation at
1940, in reference to heartbeat, from de- + fibrillation "a beating in an abnormal way," especially of the muscles of the heart that contract irregularly in this condition.
defibrillator (n.) Look up defibrillator at
1956, agent noun from defibrillation.
deficiency (n.) Look up deficiency at
1630s, from deficience (mid-15c.) + -cy; or from Late Latin deficientia, from deficientem (see deficient).
deficient (adj.) Look up deficient at
1580s, from Latin deficientem (nominative deficiens), present participle of deficere "to desert, revolt, fail," from de- "down, away" (see de-) + facere "to do, perform" (see factitious).
deficit (n.) Look up deficit at
1782, from French déficit (late 17c.), from Latin deficit "it is wanting," an introductory word in clauses of inventory, third person singular present indicative of deficere "to be deficient" (see deficient).
defilade (n.) Look up defilade at
1828, from defile (n.) + -ade.
defile (v.) Look up defile at
c. 1400, "to desecrate, profane;" mid-15c., "to make foul or dirty," alteration of earlier defoulen, from Old French defouler "trample down, violate," also "ill-treat, dishonor," from de- "down" (see de-) + foler "to tread," from Latin fullo "person who cleans and thickens cloth by stamping on it" (see foil (v.)).

The alteration (or re-formation) in English is from influence of Middle English filen (v.) "to render foul; make unclean or impure," literal and figurative, from Old English fylen (trans.), related to Old English fulian (intrans.) "to become foul, rot," from the source of foul (adj.). Compare befoul, which also had a parallel form befilen. Related: Defiled; defiling.
defile (n.) Look up defile at
"narrow passage," 1640s, especially in a military sense, "a narrow passage down which troops can march only in single file," from French défilé, noun use of past participle of défiler "march by files" (17c.), from de- "off" (see de-) + file "row," from Latin filum "thread" (see file (v.1)). The verb in this sense is 1705, from French défiler.
defilement (n.) Look up defilement at
1570s, from defile (v.) + -ment.
define (v.) Look up define at
late 14c., "to specify; to end," from Old French defenir, definir "to finish, conclude, come to an end; bring to an end; define, determine with precision," and directly from Latin definire "to limit, determine, explain," from de- "completely" (see de-) + finire "to bound, limit," from finis "boundary, end" (see finish (v.)). Related: Defined; defining.
definite (adj.) Look up definite at
1550s, from Latin definitus "defined, bounded, limited," past participle of definire (see define). Definite means "defined, clear, precise, unmistakable;" definitive means "having the character of finality."
definitely (adv.) Look up definitely at
1580s, from definite + -ly (2). As a colloquial emphatic word, attested by 1931.
definition (n.) Look up definition at
late 14c., "decision, setting of boundaries," from Old French definicion, from Latin definitionem (nominative definitio), noun of action from past participle stem of definire (see define).

In logic, meaning "act of stating what something means" is from 1640s; meaning "a statement of the essential nature of something" is from late 14c.; the special focus on words developed after c. 1550. Meaning "degree of distinctness of the details in a picture" is from 1889.
definitive (adj.) Look up definitive at
late 14c., from Old French definitif (12c.), from Latin definitivus "explanatory, definitive," from past participle stem of definire (see define). Related: Definitively.
deflagration (n.) Look up deflagration at
c. 1600, from Latin deflagrationem (nominative deflagratio) "a burning up, conflagration," noun of action from past participle stem of deflagrare, from de- (see de-) + flagrare "be ablaze, burn" (see flagrant).
deflate (v.) Look up deflate at
1891, in reference to balloons, coinage based on inflate. Latin deflare meant "to blow away," but in the modern word the prefix is taken in the sense of "down." Related: Deflated; deflating.
deflation (n.) Look up deflation at
1891, "release of air," from deflate + -ion. In reference to currency or economic situations, from 1920.
deflect (v.) Look up deflect at
1550s, from Latin deflectere "to bend (something) aside or downward," from de- "away" (see de-) + flectere "to bend" (see flexible). Originally transitive, the intransitive sense is first recorded 1640s. Related: Deflected; deflecting.
deflection (n.) Look up deflection at
also (and with more etymological propriety) deflexion, c. 1600, from Latin deflexionem, noun of action from past participle stem of deflectere (see deflect). Both forms were present 17c., but the spelling with -c- has come to predominate.
defloration (n.) Look up defloration at
late 14c., "culling of the finest passages from books," from Old French desfloracion (14c.), from Latin deflorationem "plucking of flowers," also "taking of (a woman's) virginity," noun of action from past participle stem of deflorare (see deflower). Compare also anthology. Also used in Middle English with reference to virginity from c. 1400.