amphibious (adj.)
1640s, "combining two qualities; having two modes of life," especially "living both on land and in water," from Latinized form of Greek amphibios "having a double life; living on land and in water" (see amphibian (adj.)). Of motor vehicles, from 1915.
amphibrach (n.)
1580s, from Latin amphibrachus, from Greek amphibrakhys, name for a foot consisting of a long syllable between two short, literally "short at both ends," from amphi "on both sides" (see amphi-) + brakhys "short" (from PIE root *mregh-u- "short"). Related: Amphibrachic.
Amphictyonic (adj.)
in reference to one of several ancient Greek confederations of neighboring states, 1753, probably via French, from Greek amphiktionikos, from amphiktiones "neighbors," literally "they that dwell round about," from amphi "on both sides, all around" (from PIE root *ambhi- "around") + second element related to ktizein "to create, found," ktoina "habitation, township," from PIE *kti-, metathesized form of root *tkei- "to settle, dwell, be home."

The most famous was that of Delphi. Madison and other U.S. Founders devoted close study to it. Shaftesbury has amphictyonian (1711).
amphigory (n.)
"burlesque nonsense writing or verse," 1809, from French amphigouri (18c.), which is of unknown origin, perhaps itself a nonsense word, though the first element seems to suggest Greek amphi (see amphi-). The second sometimes is said to be Greek gyros "circle," making the whole thus "circle on both sides," or it may be from Greek -agoria "speech" (as in allegory, category). Related: Amphigoric.
amphisbaena (n.)
fabled serpent of ancient times, with a head at either end, late 14c., amphibena, from Medieval Latin, from Greek amphisbaena, from amphis "both ways" (see amphi-) + stem of bainein "to go, walk, step," from PIE root *gwa- "to go, come."
Amphiscians (n.)
1620s, from Medieval Latin Amphiscii, from Greek amphiskioi "inhabitants of the tropics," literally "throwing a shadow both ways," from amphi "on both sides" (from PIE root *ambhi- "around") + skia "shadow, shade" (see Ascians). Inhabitants of torrid zones, so called because they are "people whose shadow is sometimes to the North, and sometimes to the South" [Cockerham, 1623] depending on the sun being below or above the equator. Compare Ascians.
amphitheater (n.)
late 14c., from Latin amphitheatrum, from Greek amphitheatron "double theater, amphitheater," neuter of amphitheatros "with spectators all around," from amphi "on both sides" (from PIE root *ambhi- "around") + theatron "theater" (see theater). Classical theaters were semi-circles, thus two together made an amphi-theater. They were used by the Romans especially for gladiatorial contests and combats of wild beasts.
amphitheatre (n.)
chiefly British English spelling of amphitheater. See -er.
Greek sea-nymph, wife of Poseidon; the first element appears to be amphi "round about, on both sides, all around" (see amphi-), the second trite, fem of tritos "third," but the sense intended by the compound is unclear.
amphora (n.)
early 14c., "two-handled vessel for holding wine, oil, etc.," from Latin amphora from Greek amphoreus "an amphora, jar, urn," contraction of amphiphoreus, literally "two-handled," from amphi "on both sides" (see amphi-) + phoreus "bearer," from pherein "to bear," from PIE root *bher- (1) "to carry."

Decorative amphorae were used as ornaments and given as prizes at some public games. Also a liquid measure in the ancient world, in Greece equal to 9 gallons, in Rome to 6 gallons, 7 pints. Related: Amphoral; amphoric.
amphoteric (adj.)
"neither acid nor alkaline," 1832, from Greek amphoteros "each or both of two," a variant of ampho "both" that replaced the earlier word. It is identical with Latin ambo and ultimately from the source of amphi- (q.v.). Other languages have the word without the nasal (Old Church Slavonic oba, Lithuanian abu) and Germanic has it without the initial vowel (Gothic bai). De Vaan writes, "There is no overall explanation for the forms, but connection with [amphi] seems clear."
ample (adj.)
mid-15c., "great, abundant," especially "sufficient for any purpose," from Old French ample "large, wide, vast, great" (12c.), from Latin amplus "large, spacious; abundant, numerous; magnificent, distinguished," which is related to ampla "handle, grip; opportunity," from Proto-Italic *amlo- "seizable," from a PIE root meaning "to grab" that also is postulated as the source of amare "to love" (see Amy).
amplification (n.)
1540s, "enlargement" in any dimension, from Latin amplificationem (nominative amplificatio) "a widening, extending," noun of action from past participle stem of amplificare "to enlarge, broaden, increase," from amplus "large" (see ample) + combining form of facere "to make, do" (from PIE root *dhe- "to set, put"). Originally in English often of rhetorical devices; meaning "enlargement of sound by electrical technology" is from 1915.
amplifier (n.)
1540s; agent noun from amplify. Electronic sense is from 1914; shortened form amp is from 1967. Alternative stentorphone (1921) did not catch on.
amplify (v.)
early 15c., "to enlarge, expand, increase," from Old French amplifier (15c.), from Latin amplificare "to enlarge," from amplus "large" (see ample) + combining form of facere "to make, do" (from PIE root *dhe- "to set, put"). Meaning "augment in volume or amount" is from 1570s. Restriction of use to sound seems to have emerged from c. 1915 in reference to radio technology.
amplitude (n.)
1540s, "state or quality of being ample," from Middle French amplitude or directly from Latin amplitudinem (nominative amplitudo) "wide extent, width," from amplus "large, spacious" (see ample). Amplitude modulation in reference to radio wave broadcast (as opposed to frequency modulation) first attested 1921, usually abbreviated A.M. Related: Amplitudinous.
amply (adv.)
"fully, sufficiently, copiously," 1550s, from ample + -ly (2).
ampoule (n.)
"small bottle or flask," especially one used for holy liquids, c. 1200, from Old French ampole "flask, vial," from Latin ampulla "small globular flask or bottle," which is of uncertain origin, perhaps a contracted form of amphora. Superseded in English by the form ampulla and later ampul.
ampul (n.)
1907, "sealed container holding a dose of medicine," from French ampul (1886), from Latin ampulla "flask, vial" (see ampoule). A modern borrowing of the word represented by Middle English ampoule. Related: Ampullaceous.
ampulla (n.)
type of globular ancient Roman bottle with a narrow neck, late 14c., from Latin ampulla (see ampoule, which is the same word come up through French).
amputate (v.)
1630s, "to cut off a limb," originally in English both of plants and persons; a back-formation from amputation or else from Latin amputatus, past participle of amputare "to cut off, lop off; cut around, to prune," from am(bi)- "around" (from PIE root *ambhi- "around") + putare "to prune, trim" (from PIE root *pau- (2) "to cut, strike, stamp"). Related: Amputated; amputating.
amputation (n.)
1610s, "a cutting off of tree branches, a pruning," also "operation of cutting off a limb, etc., of a body," from Middle French amputation or directly from Latin amputationem (nominative amputatio), noun of action from past participle stem of amputare "to cut off, lop off; cut around, to prune," from am(bi)- "around" (from PIE root *ambhi- "around") + putare "to prune, trim" (from PIE root *pau- (2) "to cut, strike, stamp").
amputee (n.)
1910, perhaps on a French model; see amputation + -ee.
city in Punjab, from Sanskrit amrta "immortal" (from a- "not," from PIE root *ne-, + mrta "dead," from PIE root *mer- "to rub away, harm") + saras "lake, pool."
principal city of the Netherlands; the name is a reference to the dam (see dam (n.1)) built on the Amstel river. The river name is said to be from Germanic elements ama "current" and stelle "place." Prevalence of dam in Dutch place names (Rotterdam, Edam, etc.) reflects the geography of Holland. In rhyming slang, "ram" (e.g. for one who "butts in" a queue).
amt (n.)
territorial division in Denmark and Norway, from Danish amt, from German Amt "office," from Old High German ambaht, a word of Celtic origin related to Gallo-Roman ambactus "servant" (see ambassador).
amtrac (n.)
amphibious assault vehicle, 1944, contraction of amphibious tractor (n.).
U.S. government-run railway corporation, 1971, contraction of American Track.
amuck (adv.)
17c., variant of amok; treated as a muck by Dryden, Byron, etc., and defended by Fowler, who considered amok didacticism.
amulet (n.)
mid-15c., amalettys, from Latin amuletum (Pliny) "thing worn superstitiously as a charm against spells, disease, etc.," which is of uncertain origin, perhaps related to amoliri "to avert, to carry away, remove." OED rejects Arabic origin. Not recorded again in English until c. 1600; the 15c. use may be via French. Related: Amuletic.
amusable (adj.)
1829 (from 1817 as a French word in English), from amuse (v.) + -able.
amuse (v.)
late 15c., "to divert the attention, beguile, delude," from Old French amuser "fool, tease, hoax, entrap; make fun of," literally "cause to muse" (as a distraction), from a "at, to" (from Latin ad, but here probably a causal prefix) + muser "ponder, stare fixedly" (see muse (v.)).

Original English senses obsolete; meaning "divert from serious business, tickle the fancy of" is recorded from 1630s, but through 18c. the primary meaning was "deceive, cheat" by first occupying the attention. "The word was not in reg. use bef. 1600, and was not used by Shakespere" [OED]. Bemuse retains more of the original meaning.
amused (adj.)
c. 1600, "distracted, diverted, cheated;" 1727 as "entertained;" past participle adjective from amuse (v.).
amusement (n.)
1640s, "diversion of attention," especially in military actions, from French amusement, noun of action from amuser (see amuse).
And because all bold and irreverent Speeches touching matters of high nature, and all malicious and false Reports tending to Sedition, or to the Amusement of Our People, are punishable ... (etc.) [Charles II, Proclamation of Oct. 26, 1688]
Meaning "a pastime, play, game, anything which pleasantly diverts the attention" (from duty, work, etc.) is from 1670s, originally depreciative; meaning "pleasurable diversion" attested from 1690s. Amusement hall is from 1862; amusement park first recorded 1897.
amusing (adj.)
1590s, "cheating;" present participle adjective from amuse (v.). Sense of "interesting" is from 1712; that of "pleasantly entertaining, tickling to the fancy" is by 1826. Noted late 1920s as a vogue word. Amusive has been tried in all senses since 18c. and might be useful, but it never caught on. Related: Amusingly; amusingness.
fem. proper name, from Old French Amee, literally "beloved," from fem. past participle of amer "to love," from Latin amare "to love, be in love with; find pleasure in," Proto-Italic *ama- "to take, hold," from a PIE root meaning "take hold of," also the source of Sanskrit amisi, amanti "take hold of; swear;" Avestan *ama- "attacking power;" Greek omnymi "to swear," anomotos "under oath;" Old Irish namae "enemy." According to de Vaan, "The Latin meaning has developed from 'to take the hand of' [to] 'regard as a friend'."
amygdala (n.)
part of the brain, from Latin amygdalum "almond" (which the brain parts resemble), from Greek amygdale "almond" (see almond). English also had amygdales "the tonsils" (early 15c.), from a secondary sense of the Latin word in Medieval Latin, a translation of Arabic al-lauzatani "the two tonsils," literally "the two almonds," so called by Arabic physicians for fancied resemblance.
amyl (n.)
hydrocarbon radical, 1850 (amyle), from Latin amylum "starch," from Greek amylon "fine meal, starch," noun use of neuter of adjective amylos "not ground at the mill," that is, "ground by hand," from a- "not" (see a- (3)) + myle "mill" (from PIE root *mele- "to crush, grind"). So called because first obtained from the distilled spirits of potato or grain starch (though it also is obtained from other sources). In 16c. English amyl meant "starch, fine flour."
amylase (n.)
enzyme which brings about the hydrolysis of starch, 1885, from amyl + chemical suffix -ase.
word-forming element in modern chemistry, combining form of amyl (q.v.).
amyloid (adj.)
"starch-like," 1843, coined in German (1839) from Latin amylum (see amyl) + Greek-derived suffix -oid. The noun is attested from 1872.
amyotrophic lateral sclerosis (n.)
sclerosis of the spinal cord, causing atrophy of the muscles, 1874, in translations from French. Amyotropic is compounded from Greek elements: a- "not, without" (see a- (3)) + comb. form of mys "muscle" (see muscle (n.)) + trophikos "feeding," from trophe "nourishment" (see -trophy). Often known in U.S. as Lou Gehrig's disease, after the New York Yankees baseball player (1903-1941) who was diagnosed with it in 1939.
indefinite article before words beginning with vowels, 12c., from Old English an (with a long vowel) "one; lone," also used as a prefix meaning "single, lone" (as in anboren "only-begotten," anhorn "unicorn," anspræce "speaking as one"). See one for the divergence of that word from this. Also see a, of which this is the older, fuller form.

In other European languages, identity between the indefinite article and the word for "one" remains explicit (French un, German ein, etc.). Old English got by without indefinite articles: He was a good man in Old English was he wæs god man.

In texts of Shakespeare, etc., an as a word introducing a clause stating a condition or comparison conjunction is a reduced form of and in this now-archaic sense "if" (a usage first attested late 12c.), especially before it.
an- (2)
a later form of Latin ad "to" before -n- (see ad-), as in annex, announce, annihilate.
an- (1)
privative prefix, from Greek an-, "not, without," from PIE root *ne- "not"). The Greek prefix is a fuller form of the one represented in English by a- (3).
before verbs an-, word-forming element meaning: 1. "upward, up in place or time," 2. "back, backward, against," 3. "again, anew," from Greek ana (prep.) "up, on, upon; up to, toward; throughout; back, backwards; again, anew," from an extended form of PIE root *an- (1) "on, upon, above" (see on, which is the English cognate). In old medical prescriptions, ana by itself meant "an equal quantity of each."
Anabaptism (n.)
name of a Christian doctrine (see Anabaptist), 1570s, from Late Latin anabaptismus, literally "a second baptism," from Ecclesiastical Greek anabaptismos, from ana "again, anew" (see ana-) + baptismos "baptism" (see baptism).
Anabaptist (n.)
class of Christians who regard infant baptism as invalid, 1530s, literally "one who baptizes over again," from Modern Latin anabaptista, from Late Latin anabaptismus "second baptism" (used in literal sense from 4c.), from Ecclesiastical Greek anabaptismos, from ana "again, anew" (see ana-) + baptismos "baptism" (see baptism).

Originally in English in reference to the sects that practiced adult baptism and arose in Germany from 1521. Probably so called because, as a new faith, they baptized converts who already had been baptized (as infants) in the older Catholic or older Protestant churches. Modern branches (notably Mennonites and Amish) baptize only once (adults) and do not actively seek converts. The name also was applied, usually opprobriously, to Baptists, perhaps due to the multiple immersions of their baptisms.
anabasis (n.)
1706, from Greek anabasis "military expedition," literally "a going up (from the coast)," especially in reference to the advance of Cyrus the Younger and his Greek mercenaries from near the Aegean coast into Asia, and the subsequent story of the retreat of the 10,000 narrated by Xenophon (401 B.C.E.). From anabainein "to go up, mount;" from ana "up" (see ana-) + bainein "to go, walk, step," from PIE root *gwa- "to go, come." Related: Anabatic.
anabolic (adj.)
"pertaining to the process of building up" (especially in metabolism), 1876, with -ic + Greek anabole "that which is thrown up; a mound," from anaballein "to throw or toss up," from ana "up, upward" (see ana-) + ballein "to throw" (from PIE root *gwele- "to throw, reach").