Online Etymology Dictionary

auger (n.): c. 1500, faulty separation of Middle English a nauger, from Old English nafogar "nave drill," from Proto-Germanic *nabo-gaizaz (source also of Old Norse nafarr, Old Saxon nabuger, Old High German nabuger), a compound whose first element is related to nave (n.2) and whose second is identical to Old English gar "a spear, borer" (see gar). For similar misdivisions, see adder. The same change took place in Dutch (avegaar).
aught (n.1): "something," Old English awiht "aught, anything, something," literally "e'er a whit," from Proto-Germanic *aiwi "ever" (from PIE *aiw- "vital force, life, long life, eternity;" see eon) + *wihti "thing, anything whatever" (see wight). In Shakespeare, Milton and Pope, aught and ought occur indiscriminately.
aught (n.2): "nothing, zero," faulty separation of a naught (see naught; see adder for the separation problem).
augment (v.): c. 1400, from Old French augmenter "increase, enhance" (14c.), from Late Latin augmentare "to increase," from Latin augmentum "an increase," from augere "to increase, make big, enlarge, enrich," from PIE root *aug- (1) "to increase" (source also of Sanskrit ojas- "strength;" Lithuanian augu "to grow," aukstas "high, of superior rank;" Greek auxo "increase," auxein "to increase;" Gothic aukan "to grow, increase;" Old English eacien "to increase"). Related: Augmented; augmenting. As a noun from early 15c.
augmentation (n.): mid-15c., "act of making greater," from Old French augmentacion "increase," from Late Latin augmentationem (nominative augmentatio), noun of action from past participle stem of augmentare (see augment). Meaning "amount by which something is increased" is from 1520s. Musical sense is from 1590s.
augmentative (adj.): c. 1500, from Middle French augmentatif (14c.), from Latin augmentat-, stem of augmentare (see augment).
augmented (adj.): past participle adjective from augment, c. 1600. Musical sense is attested from 1825.
augur (n.): 1540s, from Latin augur, a religious official in ancient Rome who foretold events by interpreting omens, perhaps originally meaning "an increase in crops enacted in ritual," in which case it probably is from Old Latin *augos (genitive *augeris) "increase," and is related to augere "increase" (see augment). The more popular theory is that it is from Latin avis "bird," because the flights, singing, and feeding of birds, along with entrails from bird sacrifices, were important objects of divination (compare auspicious). In that case, the second element would be from garrire "to talk."
augur (v.): c. 1600, from augur (n.). Related: Augured; auguring.
augury (n.): late 14c., "divination from the flight of birds," from Old French augure "divination, soothsaying, sorcery, enchantment," or directly from Latin augurium "divination, the observation and interpretation of omens" (see augur). Figurative sense of "omen, portent, indication" is from 1797 (also often in plural as auguries).
august (adj.): 1660s, from Latin augustus "venerable, majestic, magnificent, noble," probably originally "consecrated by the augurs, with favorable auguries" (see augur (n.)); or else "that which is increased" (see augment).
August: eighth month, 1097, from Latin Augustus (mensis), sixth month of the later Roman calendar, renamed from Sextilis (literally "sixth") in 8 B.C.E. to honor emperor Augustus Caesar, literally "Venerable Caesar" (see august (adj.)). In England, the name replaced native Weodmonað "weed month." One of two months given new names to honor Roman emperors (July being the other), the Romans also gave new imperial names to September (Germanicus) and October (Domitian) but luckily these did not stick.
Augusta: fem. proper name, Latin fem. of Augustus.
Augustan (adj.): 1640s, from Latin Augustanus, "pertaining to Augustus (Caesar)," whose reign was connected with "the palmy period of Latin literature" [OED]; hence, "period of purity and refinement in any national literature" (1712).
Augustine (adj.): c. 1400 in reference to members of the religious order named for St. Augustine the Great (354-430), bishop of Hippo. The name is Latin Augustinus, from augustus "venerable, majestic, magnificent, noble" (see august (adj.)) + name-forming inus (see -ine (1)).
Augustus: masc. proper name, from Latin augustus "venerable" (see august). The name originally was a cognomen applied to Gaius Julius Caesar Octavianus as emperor, with a sense something like "his majesty."
auk (n.): 1670s, from a Scandinavian source such as Old Norse alka, probably originally imitative of a water-bird cry (compare Latin olor "swan," Greek elea "marsh bird").
auld (adj.): variant of old that more accurately preserves the Anglo-Saxon vowel. Surviving in northern English and Scottish; distinctly Scottish after late 14c.
aunt (n.): c. 1300, from Anglo-French aunte, Old French ante (Modern French tante, from a 13c. variant), from Latin amita "paternal aunt" diminutive of *amma a baby-talk word for "mother" (source also of Greek amma "mother," Old Norse amma "grandmother," Middle Irish ammait "old hag," Hebrew em, Arabic umm "mother").

Extended senses include "an old woman, a gossip" (1580s); "a procuress" (1670s); and "any benevolent woman," in American English, where auntie was recorded since c. 1790 as "a term often used in accosting elderly women." The French word also has become the word for "aunt" in Dutch, German (Tante), and Danish. Swedish has retained the original Germanic (and Indo-European) custom of distinguishing aunts by separate terms derived from "father's sister" (faster) and "mother's sister" (moster). The Old English equivalents were faðu and modrige. In Latin, too, the formal word for "aunt on mother's side" was matertera. Some languages have a separate term for aunts-in-law as opposed to blood relations.
auntie (n.): 1787, also aunty, familiar diminutive form of aunt. As a form of kindly address to an older woman to whom one is not related, originally in southern U.S., of elderly slave women.
The negro no longer submits with grace to be called "uncle" or "auntie" as of yore. ["Harper's Magazine," October 1883]
aura (n.): 1870 in spiritualism, "subtle emanation around living beings;" earlier "characteristic impression" made by a personality (1859), earlier still "gentle breeze" (late 14c.), from Latin aura "breeze, wind, air," from Greek aura "breath, breeze," from PIE root *awer- (see air (n.1)).
aural (adj.): 1847, "pertaining to the ear," from Latin auris "ear" (see ear (n.1)) + -al (1). Meaning "received or perceived by ear" is attested from 1860. Related: Aurally.
aureate (adj.): early 15c., "gold, gold-colored," also figuratively, "splendid, brilliant," from Latin aureatus "decorated with gold," from aureus "golden," from aurum "gold," from PIE root *aus- (2) "gold" (source also of Sanskrit ayah "metal," Avestan ayo, Latin aes "brass," Old English ar "brass, copper, bronze," Gothic aiz "bronze," Old Lithuanian ausas "gold"), probably related to root *aus- "to shine" (see aurora).
aureole (n.): early 13c., from Latin aureola (corona), fem. diminutive of aureus "golden" (see aureate). In medieval Christianity, the celestial crown worn by martyrs, virgins, etc., as victors over the flesh.
auricle (n.): part of the ear, 1650s, from Latin auricula "ear," diminutive of auris (see ear (n.1)). As a chamber of the heart, early 15c., from Latin, so called from a perceived similarity in shape to an animal's ear.
auricular (adj.): 1540s, "auditory" (originally of confessions), from Medieval Latin auricularis, from Latin auricula (see auricle). Meaning "pertaining to the ear" is from 1640s.
auriferous (adj.): "containing gold," 1727, from Latin aurifer "gold-bearing," from auri-, comb. form of aurum "gold" (see aureate) + -fer "producing, bearing" (see infer).
Auriga: northern constellation, from Latin auriga "a charioteer, driver," from aureae "bridle of a horse" (from os, genitive oris, "mouth;" see oral) + agere "set in motion, drive, lead" (see act (n.)).
aurochs (n.): 1766, misapplication to the European bison (Bos bison) of a word that actually refers to a species of wild ox (Bos ursus) that went extinct 17c., from German Aurochs, from Old High German urohso, from uro "aurochs" (cognate with Old English ur, Old Norse ürr), which is of unknown origin, + ohso "ox" (see ox). Latin urus and Greek ouros are Germanic loan-words.
aurora (n.): late 14c., from Latin Aurora, the Roman goddess of dawn, from PIE *ausus- "dawn," also the name of the Indo-European goddess of the dawn, from root *aus- (1) "to shine," especially of the dawn (source also of Greek eos "dawn," auein "to dry, kindle;" Sanskrit usah, Lithuanian ausra "dawn;" Latin auster "south wind," usum "to burn;" Old English east "east").
aurora borealis (n.): 1620s, "Northern Lights," literally "northern dawn," said to have been coined by French philosopher Petrus Gassendus (1592-1655) after a spectacular display seen in France Sept. 2, 1621; see aurora + boreal. In northern Scotland and among sailors, sometimes called the dancers or the merry dancers.
auroral (adj.): 1550s, "pertaining to dawn," from aurora + -al (1). Meaning "of the color of dawn" is from 1827; "of the aurora" from 1828.
auscultate (v.): "to listen" (especially with a stethoscope), 1832, from Latin auscultatus, past participle of auscultare "to listen attentively to," from aus-, from auris "ear" (see ear (n.1)); "the rest is doubtful" [OED]. Tucker suggests the second element is akin to clinere "to lean, bend."
auscultation (n.): "act of listening," 1630s, from Latin auscultationem (nominative auscultatio), noun of action from past participle stem of auscultare (see auscultate). Medical sense is from 1821.
auspex (n.): 1590s, "one who observes flights of birds for the purpose of taking omens," from Latin auspex "interpreter of omens given by birds," from PIE *awi-spek- "observer of birds," from *awi- "bird" (see aviary) + *spek- "to see" (see scope (n.1)). Compare Greek oionos "bird of prey," also "bird of omen, omen," and ornis "bird," which also could mean "omen."
auspices (n.): plural (and now the usual form) of auspice; 1530s, "observation of birds for the purpose of taking omens," from French auspice (14c.), from Latin auspicum "divination from the flight of birds; function of an auspex" (q.v.). Meaning "any indication of the future (especially favorable)" is from 1650s; earlier (1630s) in extended sense of "benevolent influence of greater power, influence exerted on behalf of someone or something," originally in expression under the auspices of.
auspicious (adj.): 1590s, "of good omen" (implied in auspiciously), from Latin auspicium "divination by observing the flight of birds," from auspex (genitive auspicis) + -ous. Related: Auspiciously; auspiciousness.
Aussie (n.): short for Australian (n.) or Australia, attested from 1917.
auster (n.): "south wind," late 14c., from Latin auster "the south wind; the south country" (see Australia).
austere (adj.): early 14c., from Old French austere (Modern French austère) and directly from Latin austerus "dry, harsh, sour, tart," from Greek austeros "bitter, harsh," especially "making the tongue dry" (originally used of fruits, wines), metaphorically "austere, harsh," from PIE *saus- "dry" (see sere (adj.)). Use in English is figurative: "stern, severe, very simple." Related: Austerely.
austerity (n.): mid-14c., "sternness, harshness," from Old French austerite "harshness, cruelty" (14c.) and directly from Late Latin austeritatem (nominative austeritas), from austerus (see austere). Of severe self-discipline, from 1580s; hence "severe simplicity" (1875); applied during World War II to national policies limiting non-essentials as a wartime economy.
Austin: surname (also Austen) and masc. proper name, from Old French Aousten, an abbreviated form of Latin Augustine.
austral (adj.): 1540s, from Latin australis, from auster (see auster).
Australia: from Latin Terra Australis (16c.), from australis "southern" + -ia. A hypothetical southern continent, known as terra australis incognita, had been proposed since 2c. Dutch explorers called the newfound continent New Holland; the current name was suggested 1814 by Matthew Flinders as an improvement over Terra Australis "as being more agreeable to the ear, and an assimilation to the name of the other great portions of the earth" ["Voyage to Terra Australis"]. In 1817 Gov. Lachlan Macquarie, having read Flinders' suggestion, began using it in official correspondence. The ultimate source is Latin auster "south wind," hence, "the south country."

The Latin sense shift in australis, if it is indeed the same word other Indo-European languages use for east (see aurora), for which Latin uses oriens (see orient), perhaps is based on a false assumption about the orientation of the Italian peninsula, "with shift through 'southeast' explained by the diagonal position of the axis of Italy" [Buck]; see Walde, Alois, "Lateinisches etymologisches Wörterbuch," 3rd. ed., vol. 1, p.87; Ernout, Alfred, and Meillet, Alfred, "Dictionnaire étymologique de la langue latine," 2nd. ed., p.94. Or perhaps the connection is more ancient, and from PIE root *aus- "to shine," source of aurora, which also produces words for "burning," with reference to the "hot" south wind that blows into Italy. Thus auster "(hot) south wind," metaphorically extended to "south."
Australian (n.): 1690s, in reference to aboriginal inhabitants, from Australia + -an. As an adjective by 1814. Australianism in speech is attested from 1891.
Australopithecus (n.): 1925, coined by Australian anthropologist Raymond A. Dart (1893-1988) from Latin australis "southern" (see Australia) + Greek pithekos "ape." So called because first discovered in South Africa.
Austria: European nation, from Medieval Latin Marchia austriaca "eastern borderland." German Österreich is "eastern kingdom," from Old High German ostar "eastern" (see east) + reich (see Reichstag). So called for being on the eastern edge of Charlemagne's empire.
Austro-: comb. form meaning "Austrian;" see Austria.
autarchy (n.): 1660s, "absolute sovereignty," from Greek autarkhia, from autarkhein "to be an absolute ruler," from autos "self" (see auto-) + arkhein "to rule" (see archon).
autarky (n.): 1610s, "self-sufficiency," from Greek autarkeia "sufficiency in oneself, independence," from autarkes "self-sufficient, having enough, independent of others" (also used of countries), from autos "self" (see auto-) + arkein "to ward off, keep off," also "to be strong enough, sufficient," from PIE root *ark- "to hold, contain, guard" (see arcane). From a different Greek source than autarchy, and thus the spelling. As a term in international economics, prominent late 1930s. Related: Autarkic.