asthenosphere (n.) Look up asthenosphere at Dictionary.com
layer of the Earth's upper mantle, 1914, literally "sphere of weakness" (by comparison with the lithosphere), from Greek asthenes "weak" (see asthenia) + sphere.
asthma (n.) Look up asthma at Dictionary.com
"respiratory disorder characterized by paroxysms of labored breathing and a feeling of contraction in the chest," late 14c., asma, asma, from Latin asthma, from Greek asthma "shortness of breath, a panting," from azein "breathe hard," probably related to anemos "wind," from PIE root *ane- "to breathe" (see animus). The -th- was restored in English 16c.
asthmatic (adj.) Look up asthmatic at Dictionary.com
"pertaining to or afflicted with asthma," 1540s, from Latin asthmaticus, from Greek asthmatikos, from asthma "shortness of breath" (see asthma). Noun meaning "person with asthma" is recorded from 1610s.
astigmatic (adj.) Look up astigmatic at Dictionary.com
"exhibiting astigmatism," 1849; see astigmatism + -ic.
astigmatism (n.) Look up astigmatism at Dictionary.com
"defect in the structure of the eye whereby the rays of light do not converge to a point upon the retina," 1849, coined by the Rev. William Whewell (1794-1866), English polymath, from Greek a- "without" (see a- (3)) + stigmatos genitive of stigma "a mark, spot, puncture," from PIE root *steig- "to stick; pointed" (see stick (v.)).
astir (adv.) Look up astir at Dictionary.com
"up and about," 1823, from phrase on the stir, or from Scottish asteer; from a- (1) + stir (see stir (v.)). Old English had astyrian, which yielded Middle English ben astired "be stirred up, excited, aroused."
astonish (v.) Look up astonish at Dictionary.com
c. 1300, astonien, "to stun, strike senseless," from Old French estoner "to stun, daze, deafen, astound," from Vulgar Latin *extonare, from Latin ex "out" (see ex-) + tonare "to thunder" (see thunder (n.)); so, literally "to leave someone thunderstruck." The modern form (influenced by English verbs in -ish, such as distinguish, diminish) is attested from 1520s. The meaning "amaze, shock with wonder" is from 1610s.
No wonder is thogh that she were astoned [Chaucer, "Clerk's Tale"]
Related: Astonished; astonishing.
astonishing (adj.) Look up astonishing at Dictionary.com
"causing wonder or amazement," 1620s, present-participle adjective from astonish. Related: Astonishingly.
astonishment (n.) Look up astonishment at Dictionary.com
1590s, state of being amazed or shocked with wonder;" see astonish + -ment. Earlier it meant "paralysis" (1570s).
astound (v.) Look up astound at Dictionary.com
mid-15c., from Middle English astouned, astoned (c. 1300), past participle of astonen, astonien "to stun" (see astonish), with more of the original sense of Vulgar Latin *extonare. The unusual form is perhaps because the past participle was so much more common it came to be taken for the infinitive, or/and by the same pattern which produced round (v.) from round (adj.), or by the intrusion of an unetymological -d as in sound (n.1). Related: Astounded; astounding.
astounding (adj.) Look up astounding at Dictionary.com
"stunning," 1580s, present-participle adjective from astound (v.). Related: Astoundingly.
astral (adj.) Look up astral at Dictionary.com
c. 1600, "pertaining to the stars," from Late Latin astralis, from Latin astrum "star," from Greek astron "a star" (see star (n.)). Meaning "pertaining to supersensible substances" is from 1690s, popularized late 19c. in Theosophy.
astray (adv.) Look up astray at Dictionary.com
c. 1300, astraied "away from home; lost, wandering," borrowed and partially nativized from Old French estraie, past participle of estraier "astray, riderless (of a horse), lost," literally "on stray" (see stray (v.)).
astriction (n.) Look up astriction at Dictionary.com
"act of binding close or constricting," especially contraction by applications, 1560s, from Latin astrictionem (nominative astrictio), noun of action from past participle stem of astringere "to bind fast, tighten, contract," from assimilated form of ad "to" (see ad-) + stringere "draw tight" (see strain (v.)). Related: Astrictive (1550s). As verbs, astrict is from 1510s; astringe from 1520s.
Astrid Look up Astrid at Dictionary.com
fem. proper name, from Norse; it is cognate with Old High German Ansitruda, from ansi "god" (see Aesir) + trut "beloved, dear."
astride (adv.) Look up astride at Dictionary.com
"with one leg on each side," 1660s, from a- (1) "on" + stride (n.).
astringent (adj.) Look up astringent at Dictionary.com
1540s, "binding, contracting," from Latin astringentum (nominative astringens), present participle of astringere "to bind fast, tighten, contract," from assimilated form of ad "to" (see ad-) + stringere "draw tight" (see strain (v.)). Related: Astringently; astringency. As a noun from 1620s, "an astringent substance, something which contracts tissues and thereby checks discharge of blood."
astro- Look up astro- at Dictionary.com
element active in English word formation from mid-18c. and meaning "star or celestial body; outer space," from Greek astro-, stem and comb. form of astron "star," which is related to aster "star," from PIE root *ster- (2) "star" (see star (n.)). In ancient Greek, aster typically was "a star" and astron mostly in plural, "the stars." In singular it mostly meant "Sirius" (the brightest star).
astrobiology (n.) Look up astrobiology at Dictionary.com
1903, from French astrobiologie; see astro- + biology. Related: Astrobiological; astrobiologist.
astrobleme (n.) Look up astrobleme at Dictionary.com
"crypto-explosion structure on Earth caused by meteorite or asteroid impact," 1961, literally "star-wound," from astro- + Greek bleme "throw of a missile; wound caused by a missile," from ballein "to throw" (see ballistics). Coined by U.S. geologist Robert S. Dietz (1914-1995).
astrognosy (n.) Look up astrognosy at Dictionary.com
"knowledge of the fixed stars, their names, magnitudes, etc.," 1871, from astro- + -gnosy, from Greek gnosis "a knowing, knowledge," from PIE root *gno- "to know" (see gnostic (adj.)).
astrography (n.) Look up astrography at Dictionary.com
"the mapping of the fixed stars," 1740, from astro- + -graphy. Related: Astrographic.
astroid (adj.) Look up astroid at Dictionary.com
"star-shaped," 1897, from Greek astroeides, from astron "star" (see astro-) + -oeides (see -oid).
astrolabe (n.) Look up astrolabe at Dictionary.com
mid-14c., from Old French astrelabe, from Medieval Latin astrolabium, from Greek astrolabos (organon) "star taking (instrument)," from astron "star" (see astro-) + lambanien "to take" (see lemma).
astrologer (n.) Look up astrologer at Dictionary.com
late 14c., from astrology + -er (1). Drove out French import astrologein, which, had it survived, probably would have yielded *astrologian, as in Chaucer's "The wise Astrologen." Earliest recorded reference is to roosters as announcers of sunrise.
astrological (adj.) Look up astrological at Dictionary.com
1590s; see astrology + -ical. Related: Astrologically.
astrology (n.) Look up astrology at Dictionary.com
late 14c., from Latin astrologia "astronomy, the science of the heavenly bodies," from Greek astrologia "telling of the stars," from astron "star" (see astro-) + -logia "treating of" (see -logy).

Originally identical with astronomy, it had also a special sense of "practical astronomy, astronomy applied to prediction of events." This was divided into natural astrology "the calculation and foretelling of natural phenomenon" (tides, eclipses, etc.), and judicial astrology "the art of judging occult influences of stars on human affairs" (also known as astromancy, 1650s). Differentiation between astrology and astronomy began late 1400s and by 17c. this word was limited to "reading influences of the stars and their effects on human destiny."
astronaut (n.) Look up astronaut at Dictionary.com
coined 1929 in science fiction, popularized from 1961 by U.S. space program, from astro- + nautes "sailor" (see naval). French astronautique (adj.) had been coined 1927 by "J.H. Rosny," pen name of Belgian-born science fiction writer Joseph Henri Honoré Boex (1856-1940) on model of aéronautique, and Astronaut was used in 1880 as the name of a fictional spaceship by English writer Percy Greg (1836-1889) in "Across the Zodiac."
astronautics (n.) Look up astronautics at Dictionary.com
1929, see astronaut + -ics.
astronomer (n.) Look up astronomer at Dictionary.com
late 14c., from astronomy (q.v.), replacing French import astronomyen (c. 1300), which, had it survived, probably would have yielded *astronomian. Still in Shakespeare used in places where we would write astrologer.
astronomical (adj.) Look up astronomical at Dictionary.com
1550s, from astronomy + -ical. Popular meaning "immense, concerning very large figures" (as sizes and distances in astronomy) is attested from 1899. Astronomical unit (abbreviation A.U.) "mean distance from Earth to Sun," used as a unit of measure of distance in space, is from 1909. Related: Astronomically.
astronomy (n.) Look up astronomy at Dictionary.com
c. 1200, from Old French astrenomie, from Latin astronomia, from Greek astronomia, literally "star regulating," from astron "star" (see astro-) + nomos "arranging, regulating; rule, law" from PIE root *nem- "to divide, distribute, allot" (see nemesis). Used earlier than astrology and originally including it.
Þer wes moni god clarc to lokien in þan leofte, to lokien i þan steorren nehʒe and feorren. þe craft is ihate Astronomie. [Layamon, "The Brut," c. 1200]
astrophotography (n.) Look up astrophotography at Dictionary.com
1858, from astro- + photography.
astrophysicist (n.) Look up astrophysicist at Dictionary.com
1869, usually hyphenated at first, from astro- + physicist. Astrophysics is recorded from 1877.
Astroturf (n.) Look up Astroturf at Dictionary.com
1966, proprietary name for a kind of artificial grass, so called because it was used first in the Houston, Texas, Astrodome, indoor sports stadium. See astro- + turf. Houston was a center of the U.S. space program.
astute (adj.) Look up astute at Dictionary.com
1610s, from Latin astutus "crafty, wary, shrewd; sagacious, expert," from astus "cunning, cleverness, adroitness," which is of uncertain origin. The Romans considered it to be from Greek asty "town," borrowed into Latin and with an overtone of "city sophistication" (compare asteism). Related: Astutely; astuteness.
Astyanax Look up Astyanax at Dictionary.com
son of Hector and Andromache ("Iliad"), Greek, literally "lord of the city," from asty "city" (see asteism) + anax "chief, lord, master." Also the epithet of certain gods.
asunder (adv.) Look up asunder at Dictionary.com
mid-12c., contraction of Old English on sundran (see sunder). Middle English used to know asunder for "distinguish, tell apart."
asylum (n.) Look up asylum at Dictionary.com
early 15c., earlier asile (late 14c.), from Latin asylum "sanctuary," from Greek asylon "refuge," noun use of neuter of asylos "inviolable, safe from violence," especially of persons seeking protection, from a- "without" + syle "right of seizure." So literally "an inviolable place." General sense of "safe or secure place" is from 1640s; meaning "benevolent institution to shelter some class of persons" is from 1776.
asymmetrical (adj.) Look up asymmetrical at Dictionary.com
1680s; see asymmetry + -ical. Other forms that have served as an adjective based on asymmetry are asymmetral (1620s), asymmetrous (1660s), and asymmetric (1875); only the last seems to have any currency. Related: Asymmetrically.
asymmetry (n.) Look up asymmetry at Dictionary.com
1650s, "want of symmetry or proportion," from Greek asymmetria, noun of quality from asymmetros "having no common measure; disproportionate, unsymmetrical," from a- "not" + symmetros "commensurable" (see symmetry).
asymptomatic (adj.) Look up asymptomatic at Dictionary.com
"without symptoms," 1856, from a- (3) "not, without" + symptomatic.
asymptote (n.) Look up asymptote at Dictionary.com
"straight line continually approaching but never meeting a curve," 1650s, from Greek asymptotos "not falling together," from a- "not" + syn "with" + ptotos "fallen," verbal adjective from piptein "to fall" (see symptom). Related: Asymptotic.
asymptotic (adj.) Look up asymptotic at Dictionary.com
1670s, see asymptote + -ic. Related: Asymptotical; asymptotically.
asynchronous (adj.) Look up asynchronous at Dictionary.com
1748, from a- "not, without" (see a- (3)) + synchronous.
asyndetic (adj.) Look up asyndetic at Dictionary.com
1823; see asyndeton + -ic.
asyndeton (n.) Look up asyndeton at Dictionary.com
"omission of conjunctions," 1580s, from Latin, from Greek asyndeton, neuter of asyndetos "unconnected," from a- "not, without" (see a- (3)) + syndetos, from syndein "to bind together," from syn- "together" (see syn-) + dein "to bind," related to desmos "band," from PIE *de- "to bind."
asystole (n.) Look up asystole at Dictionary.com
1860, from Modern Latin, from Greek a- "not, without" (see a- (3)) + systole "contraction" (see systole).
at (prep.) Look up at at Dictionary.com
Old English æt, from Proto-Germanic *at (source also of Old Norse, Gothic at, Old Frisian et, Old High German az), from PIE *ad- "to, near, at" (source also of Latin ad "to, toward" Sanskrit adhi "near;" see ad-).

Lost in German and Dutch, which use their equivalent of to; in Scandinavian, however, to has been lost and at fills its place. In choosing between at church, in church, etc. at is properly distinguished from in or on by involving some practical connection; a worshipper is at church; a tourist is in the church.

The colloquial use of at after where ("where it's at") is attested from 1859. At last is recorded from late 13c.; adverbial phrase at least was in use by 1775. At in Middle English was used freely with prepositions (as in at after, which is in Shakespeare), but this has faded with the exception of at about.
at all (prep.) Look up at all at Dictionary.com
"in any way," mid-14c., originally used only affirmatively (as in I Samuel xx.6 in KJV: "If thy father at all misse me"); now it is overwhelmingly used only in the negative or in interrogatory expressions, or in literary attempts at Irish dialect.