actuarial (adj.) Look up actuarial at Dictionary.com
1853, from actuary + -al (1). Related: Actuarially.
actuary (n.) Look up actuary at Dictionary.com
1550s, "registrar, clerk," from Latin actuarius "copyist, account-keeper," from actus "public business" (see act (n.)). Modern insurance office meaning first recorded 1849.
actuate (v.) Look up actuate at Dictionary.com
1590s, from Medieval Latin actuatus, past participle of actuare, from Latin actus (see act (n.)). Related: Actuated; actuating.
acuity (n.) Look up acuity at Dictionary.com
early 15c., from Middle French acuité (16c.) or directly from Medieval Latin acuitatem (nominative acuitas) "sharpness," from Latin acuere "to sharpen," related to acus "needle," acuere "to sharpen," from PIE root *ak- "rise to a point, be sharp" (see acrid).
acumen (n.) Look up acumen at Dictionary.com
1530s, from Latin acumen "a point, sting," hence "mental sharpness, shrewdness," from acuere "to sharpen" (see acuity).
acupressure (n.) Look up acupressure at Dictionary.com
1859, from Latin acus "needle" (see acuity) + pressure (n.).
acupuncture (n.) Look up acupuncture at Dictionary.com
1680s, "pricking with a needle" to ease pain, from Latin acus "needle" (see acuity) + puncture. The verb is first recorded 1972.
acupuncturist (n.) Look up acupuncturist at Dictionary.com
1843, from acupuncture + -ist.
acute (adj.) Look up acute at Dictionary.com
late 14c., originally of fevers and diseases, "coming and going quickly" (opposed to a chronic), from Latin acutus "sharp, pointed," figuratively "shrill, penetrating; intelligent, cunning," past participle of acuere "sharpen" (see acuity). Meaning "sharp, irritating" is from early 15c. Meaning "intense" is from 1727. Related: Acutely; acuteness.
ad (n.) Look up ad at Dictionary.com
1841, shortened form of advertisement. Long resisted by those in the trade, and according to Mencken (1945) denounced by William C. D'Arcy (president of Associated Advertising Clubs of the World) as "the language of bootblacks, ... beneath the dignity of men of the advertising profession."
ad hoc Look up ad hoc at Dictionary.com
Latin, literally "for this (specific purpose)."
ad hominem Look up ad hominem at Dictionary.com
c. 1600, Latin, literally "to a man," from ad "to" (see ad-) + hominem, accusative of homo "man" (see homunculus).
ad infinitum Look up ad infinitum at Dictionary.com
"endlessly," Latin, literally "to infinity" from ad "to" (see ad-) + infinitum "infinity," neuter of adjective infinitus "endless" (see infinite). English version to infinity is attested from 1630s.
ad lib Look up ad lib at Dictionary.com
1811, shortened from Latin ad libitum "at one's pleasure, as much as one likes" (c. 1600), from ad "to" (see ad-) + libitum, accusative of libere "to please" (see libido). First recorded as one word 1919 (v.), 1925 (n.).
ad nauseam Look up ad nauseam at Dictionary.com
"to a sickening extent," Latin, literally "to sickness," from ad "to" (see ad-) + nauseam, accusative of nausea (see nausea).
ad valorem Look up ad valorem at Dictionary.com
type of customs duties, 1711, Modern Latin, "(in proportion) to the value," from ad "to" (see ad-) + Late Latin valorem, accusative of valor "value" (see value (n.)).
ad- Look up ad- at Dictionary.com
word-forming element expressing direction toward or in addition to, from Latin ad "to, toward" in space or time; "with regard to, in relation to," as a prefix, sometimes merely emphatic, from PIE *ad- "to, near, at" (cognate with Old English æt; see at). Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al-, etc., in conformity with the following consonant (as in affection, aggression). In Old French, reduced to a- in all cases (an evolution already underway in Merovingian Latin), but written forms in French were refashioned after Latin in 14c. and English did likewise 15c. in words it had picked up from Old French. In many cases pronunciation followed the shift.
Ada Look up Ada at Dictionary.com
fem. proper name, from Hebrew Adha, literally "ornament."
adage (n.) Look up adage at Dictionary.com
"brief, familiar proverb," 1540s, Middle French adage, from Latin adagium "adage, proverb," apparently from adagio, from ad- "to" (see ad-) + *agi-, root of aio "I say," from PIE *ag- "to speak." But Tucker thinks the second element is rather ago "set in motion, drive, urge."
adagio (adv.) Look up adagio at Dictionary.com
c. 1746, in music, "slowly, leisurely and gracefully," Italian, from ad agio, from ad "to, at" (see ad-) + agio "leisure," from Vulgar Latin adiacens, present participle of adiacere "to lie at, to lie near" (compare adjacent). In noun sense of "a slow movement," first attested 1784.
Adam Look up Adam at Dictionary.com
masc. proper name, Biblical name of the first man, progenitor of the human race, from Hebrew adam "man," literally "(the one formed from the) ground" (Hebrew adamah "ground"); compare Latin homo "man," humanus "human," humus "earth, ground, soil." To not know (someone) from Adam "not know him at all" is first recorded 1784.
Adam's apple (n.) Look up Adam's apple at Dictionary.com
1731, corresponding to Latin pomum Adami, perhaps an inexact translation of Hebrew tappuah haadam, literally "man's swelling," from ha-adam "the man" + tappuah "anything swollen." The reference is to the legend that a piece of the forbidden fruit (commonly believed to be an apple) that Eve gave Adam stuck in his throat. The term is mentioned in early 15c. as the name of an actual oriental and Mediterranean fruit, a variety of lime with an indentation fancied to resemble the marks of Adam's teeth.
adamant (adj.) Look up adamant at Dictionary.com
late 14c., "hard, unbreakable," from adamant (n.). Figurative sense of "unshakeable" first recorded 1670s. Related: Adamantly; adamance.
adamant (n.) Look up adamant at Dictionary.com
mid-14c., from Old French adamant and directly from Latin adamantem (nominative adamas) "adamant, hardest iron, steel," also figuratively, of character, from Greek adamas (genitive adamantos) "unbreakable, inflexible" metaphoric of anything unalterable, also the name of a hypothetical hardest material, perhaps literally "invincible," from a- "not" + daman "to conquer, to tame" (see tame (adj.)), or else a word of foreign origin altered to conform to Greek.

Applied in antiquity to a metal resembling gold (Plato), white sapphire, magnet (by Ovid, perhaps via confusion with Latin adamare "to love passionately"), steel, emery stone, and especially diamond (see diamond). "The name has thus always been of indefinite and fluctuating sense" [Century Dictionary]. The word was in Old English as aðamans "a very hard stone."
adamantine (adj.) Look up adamantine at Dictionary.com
c. 1200, from Latin adamantinus "hard as steel, inflexible," from Greek adamantinos, from adamas (see adamant (n.)).
Adamite (n.) Look up Adamite at Dictionary.com
"human being, descendant of Adam" the Biblical first man, 1630s, from Adam + -ite (1). Used from 1620s in reference to sects or groups that practice nudism, in reference to the state of Adam before the Fall.
adapt (v.) Look up adapt at Dictionary.com
early 15c. (implied in adapted) "to fit (something, for some purpose)," from Middle French adapter (14c.), from Latin adaptare "adjust," from ad- "to" (see ad-) + aptare "to join," from aptus "fitted" (see apt). Meaning "to undergo modification so as to fit new circumstances" (intransitive) is from 1956. Related: Adapting.
adaptability (n.) Look up adaptability at Dictionary.com
1660s, from adapt + -ability.
adaptable (adj.) Look up adaptable at Dictionary.com
1800, from adapt + -able.
adaptation (n.) Look up adaptation at Dictionary.com
c. 1600, "action of adapting," from French adaptation, from Late Latin adaptationem (nominative adaptatio), noun of action from past participle stem of adaptare (see adapt). Meaning "condition of being adapted" is from 1670s. Sense of "modification of a thing to suit new conditions" is from 1790. Biological sense first recorded 1859 in Darwin's writings.
adapter (n.) Look up adapter at Dictionary.com
1801, agent noun from adapt. Electrical engineering sense from 1907.
add (v.) Look up add at Dictionary.com
late 14c., "to join or unite (something to something else)," from Latin addere "add to, join, attach, place upon," from ad- "to" (see ad-) + -dere comb. form meaning "to put, place," from dare "to give" (see date (n.1)). Meaning "to do sums, do addition" also is from late 14c. Related: Added; adding. To add up "make sense" is from 1942.
add-on (n.) Look up add-on at Dictionary.com
"additional component," 1941, from add (v.) + on.
added (adj.) Look up added at Dictionary.com
"additional," c. 1600, past participle adjective from add (v.).
addendum (n.) Look up addendum at Dictionary.com
1794, literally "something added," from Latin addendum, neuter of addendus "that which is to be added," gerundive of addere (see add (v.)). Classical plural form is addenda.
adder (n.) Look up adder at Dictionary.com
Old English næddre "a snake, serpent, viper," from Proto-Germanic *nædro "a snake" (source also of Old Norse naðra, Middle Dutch nadre, Old High German natra, German Natter, Gothic nadrs), from PIE root *netr- (source also of Latin natrix "water snake," probably by folk-association with nare "to swim;" Old Irish nathir, Welsh neidr "adder").

The modern form represents a faulty separation 14c.-16c. into an adder, for which see also apron, auger, nickname, humble pie, umpire. Nedder is still a northern English dialect form. Folklore connection with deafness is via Psalm lviii:1-5. The adder is said to stop up its ears to avoid hearing the snake charmer called in to drive it away. Adderbolt (late 15c.) was a former name for "dragonfly."
addict (v.) Look up addict at Dictionary.com
1530s (implied in addicted), from Latin addictus, past participle of addicere "to deliver, award, yield; give assent, make over, sell," figuratively "to devote, consecrate; sacrifice, sell out, betray" from ad- "to" (see ad-) + dicere "say, declare" (see diction), but also "adjudge, allot." Earlier in English as an adjective, "delivered, devoted" (1520s). Related: Addicted; addicting.
addict (n.) Look up addict at Dictionary.com
1909, in reference to morphine, from addict (v.).
addicted (adj.) Look up addicted at Dictionary.com
1530s, "delivered over" by judicial sentence; past participle adjective from addict (v.). Modern sense of "dependent" is short for self-addicted "to give over or award (oneself) to someone or some practice" (1560s; exact phrase from c. 1600); specialization to narcotics dependency is from c. 1910.
addiction (n.) Look up addiction at Dictionary.com
c. 1600, "tendency," of habits, pursuits, etc.; 1640s as "state of being self-addicted," from Latin addictionem (nominative addictio) "an awarding, a devoting," noun of action from past participle stem of addicere (see addict (v.)). Earliest sense was less severe: "inclination, penchant," but this has become obsolete. In main modern sense it is first attested 1906, in reference to opium (there is an isolated instance from 1779, with reference to tobacco).
addictive (adj.) Look up addictive at Dictionary.com
1815, a word in chemistry and medicine; 1939 in the narcotics sense, from addict (v.) + -ive. Related: Addictively; addictiveness.
addition (n.) Look up addition at Dictionary.com
late 14c., "action of adding numbers;" c. 1400, "that which is added," from Old French adition "increase, augmentation" (13c.), from Latin additionem (nominative additio) "an adding to, addition," noun of action from past participle stem of addere (see add). Phrase in addition to "also" is from 1680s.
additional (adj.) Look up additional at Dictionary.com
1640s, from addition + -al (1). Related: Additionally.
additive (adj.) Look up additive at Dictionary.com
1690s, "tending to be added," from Latin additivus "added, annexed," from past participle stem of addere (see addition).
additive (n.) Look up additive at Dictionary.com
"something that is added" to a chemical solution or food product, 1945, from additive (adj.).
addle (v.) Look up addle at Dictionary.com
1712, from addle (n.) "urine, liquid filth," from Old English adela "mud, mire, liquid manure" (cognate with Old Swedish adel "urine," Middle Low German adel, Dutch aal "puddle").

Used in noun phrase addle egg (mid-13c.) "egg that does not hatch, rotten egg," literally "urine egg," a loan-translation of Latin ovum urinum, which is itself an erroneous loan-translation of Greek ourion oon "putrid egg," literally "wind egg," from ourios "of the wind" (confused by Roman writers with ourios "of urine," from ouron "urine"). Because of this usage, from c. 1600 the noun in English was taken as an adjective meaning "putrid," and thence given a figurative extension to "empty, vain, idle," also "confused, muddled, unsound" (1706). The verb followed a like course. Related: Addled; addling.
address (v.) Look up address at Dictionary.com
early 14c., "to guide or direct," from Old French adrecier "go straight toward; straighten, set right; point, direct" (13c.), from Vulgar Latin *addirectiare "make straight," from Latin ad "to" (see ad-) + *directiare, from Latin directus "straight, direct" (see direct (v.)). Late 14c. as "to set in order, repair, correct." Meaning "to write as a destination on a written message" is from mid-15c. Meaning "to direct spoken words (to someone)" is from late 15c. Related: Addressed; addressing.
address (n.) Look up address at Dictionary.com
1530s, "dutiful or courteous approach," from address (v.) and from French adresse. Sense of "formal speech" is from 1751. Sense of "superscription of a letter" is from 1712 and led to the meaning "place of residence" (1888).
addressee (n.) Look up addressee at Dictionary.com
1810; see address (v.) + -ee.
adduce (v.) Look up adduce at Dictionary.com
early 15c., from Latin adducere "lead to, bring to, bring along," from ad- "to" (see ad-) + ducere "to lead" (see duke (n.)). Related: Adduced; adducing.