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 white sapphire, magnet (perhaps via confusion with Latin adamare "to love passionately"), steel, emery stone, and especially diamond (see diamond). 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 of 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 "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" (cognates: Old Norse naðra, Middle Dutch nadre, Old High German natra, German Natter, Gothic nadrs), from PIE root *netr- (cognates: 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). 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 1681.
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.
Adelaide Look up Adelaide at Dictionary.com
fem. proper name, from French Adélaide, from a Germanic source similar to Old High German Adalhaid, from adal "noble family" (see atheling) + German heit "state, rank," related to Old English -had "person, degree, state, nature" (see -hood). The first element affixed to French fem. ending -ine gave Adeline.
Adeline Look up Adeline at Dictionary.com
fem. proper name, from French, of Germanic origin, literally "noble" (see Adelaide).
Adelphia Look up Adelphia at Dictionary.com
district of London, so called because it was laid out by four brothers of a family named Adam, from Greek adelphos "brother," literally "from the same womb," from copulative prefix a- "together with" + delphys "womb," perhaps related to dolphin. The district was the site of a popular theater c.1882-1900, which gave its name to a style of performance.
Aden Look up Aden at Dictionary.com
place in southern Arabia, ultimately from Akkadian edinnu "plain," which some think also is the root of Biblical Eden.
adenine (n.) Look up adenine at Dictionary.com
crystaline base, 1885, coined by German physiologist/chemist Albrecht Kossel (1853-1927) from Greek aden "gland" (see inguinal) + chemical suffix -ine (2). So called because it was derived from the pancreas of an ox.
adenoid (adj.) Look up adenoid at Dictionary.com
1839, "gland-like," medical Latin adenoideus, from Greek adenoeides, from aden (genitive adenos) "gland" (see inguinal) + eidos "form" (see -oid). Adenoids "adenoid growths" attested by 1862.
adenoidal (adj.) Look up adenoidal at Dictionary.com
1852, from adenoids (see adenoid) + -al (1).
adept (adj.) Look up adept at Dictionary.com
1690s, "completely skilled" from Latin adeptus "having reached, attained," past participle of adipisci "to come up with, arrive at," figuratively "to attain to, acquire," from ad- "to" (see ad-) + apisci "grasp, attain," related to aptus "fitted" (see apt). Related: Adeptly.
adept (n.) Look up adept at Dictionary.com
"an expert," especially "one who is skilled in the secrets of anything," 1660s, from Latin adeptus (see adept (adj.)). The Latin adjective was used as a noun in this sense in Medieval Latin among alchemists.
adequate (adj.) Look up adequate at Dictionary.com
1610s, from Latin adaequatus "equalized," past participle of adaequare "to make equal to," from ad- "to" (see ad-) + aequare "make level," from aequus (see equal). The sense is of being "equal to what is required." Related: Adequateness.
adequately (adv.) Look up adequately at Dictionary.com
1620s, from adequate + -ly (2); originally a term in logic in reference to correspondence of ideas and objects. Meaning "suitably" is recorded from 1680s.
adhere (v.) Look up adhere at Dictionary.com
1590s, from Middle French adhérer (15c.) or directly from Latin adhaerare "to stick to" (see adherent). Originally often of persons, "to cleave to a leader, cause, party, etc." (compare adherent, still often used in this sense). Related: Adhered; adhering.
adherence (n.) Look up adherence at Dictionary.com
mid-15c., "attachment to a person, support," from Middle French adhérence, from Latin adhaerentia, noun of action from adhaerentem (nominative adhaerens), present participle of adhaerare (see adherent).
adherent (adj.) Look up adherent at Dictionary.com
late 14c., from Old French adherent or directly from Latin adhaerentem (nominative adhaerens), present participle of adhaerere "stick to," from ad- "to" (see ad-) + haerere "to stick" (see hesitation).
adherent (n.) Look up adherent at Dictionary.com
"follower, associate, supporter," early 15c., from Old French adherent or directly from Latin adhaerentem (see adherent (adj.)). Meaning "adhesive substance" is from 1912.
adhesion (n.) Look up adhesion at Dictionary.com
1620s, from French adhésion or directly from Latin adhaesionem (nominative adhaesio) "a sticking to," noun of action from past participle stem of adhaerare (see adherent).
Adhesion is generally used in the material, and adherence in the metaphysical sense. [Johnson]
adhesive (adj.) Look up adhesive at Dictionary.com
1660s, from French adhésif, formed in French from Latin adhaes-, past participle stem of adhaere (see adherent).
adhesive (n.) Look up adhesive at Dictionary.com
1881, from adhesive (adj.). Originally of postage stamps (adhesive stamp is attested from 1840). Of substances that cause to adhere by 1900.
adiabatic (adj.) Look up adiabatic at Dictionary.com
1838, from Greek adiabatos "not to be passed through," from a- "not" + dia "through" (see dia-) + batos "passable," from bainein "to go" (see come).
adieu Look up adieu at Dictionary.com
late 14c., adewe, from French adieu, from phrase a dieu (vous) commant "I commend (you) to God," from a "to" (see ad) + dieu "God," from Latin deum, accusative of deus "god," from PIE *deiwos (see Zeus). Originally said to the party left; farewell was to the party setting forth.
adios Look up adios at Dictionary.com
1837, American English, from Spanish adios, from phrase a dios vos acomiendo "I commend you to God" (see adieu).
adipose (adj.) Look up adipose at Dictionary.com
1743, from Modern Latin adiposus "fatty," from Latin adipem (nominative adeps, genitive adipis) "soft fat of animals, fat, lard," from Greek aleipha "unguent, fat," related to lipos "grease, fat" (see leave (v.)). Change of -l- to -d- "prob. due to Umbrian influence" [Klein]. But it could as well be a native Italic formation from the same roots, *ad-leip-a "sticking onto."