Online Etymology Dictionary

buckwheat (n.): 1540s, from Middle Dutch boecweite "beech wheat" (cf. Danish boghvede, Swedish bovete, German Buchweizen), so called from resemblance between grains and seed of beech trees. Possibly a native formation on the same model as the Dutch word, from a dialectal form of beech. See beech + wheat.
bucolic (adj.): 1610s, earlier bucolical (1520s), from Latin bucolicus, from Greek boukolikos "pastoral, rustic," from boukolos "cowherd, herdsman," from bous "cow" (see cow (n.)) + -kolos "tending," related to Latin colere "to till (the ground), cultivate, dwell, inhabit" (the root of colony). Middle Irish búachaill, Welsh bugail "shepherd" are Celtic words form from the same root material as Greek boukolos.
bud (n.): late 14c., budde, origin unknown, perhaps from Old French boter "push forward, thrust," itself a Germanic word (cf. Dutch bot "bud," Old Saxon budil "bag, purse," German Beutel), or perhaps from Old English budd "beetle."
bud (v.): c.1400; see bud (n.). Related: Budded; budding.
Budapest: Hungarian capital, formed 1872 from merger of two cities on opposite shores of the Danube, Buda (probably from a word originally meaning "water") + Pest, a Hungarian word meaning "furnace, oven, cove," also in Slavic (cf. Russian pech'). Cf. Ofen, literally "oven," the old German name for the place.
Buddha (n.): 1680s, from Pali, literally "awakened, enlightened," past participle of budh "to awake, know, perceive," related to Sanskrit bodhati "is awake, observes, understands" (see bid). Title given by his adherents to the man who taught this path, Siddhartha Gautama, also known to them as Sakyamuni "Sage of the Sakyas" (his family clan), who lived in northern India 5c. B.C.E.
Buddhism (n.): 1801, from Buddha + -ism.
Buddhist (n.): 1810, from Buddha + -ist. An earlier word in this sense was a direct borrowing of Sanskrit Bauddha "follower of Buddha" (1801 in English), hence early erroneous hybrid compounds such as Boudhist, Bauddhist.
buddy (n.): 1850, American English, possibly an alteration of brother, or from British colloquial butty "companion" (1802), itself perhaps a variant of booty in booty fellow "confederate who shares plunder" (1520s). But butty, meaning "work-mate," also was a localized dialect word in England and Wales, attested since 18c., and long associated with coal miners. Short form bud is attested from 1851. Reduplicated form buddy-buddy (adj.) attested by 1952, American English.
Lenny Kent, a long-time fave here, is really in his element. ... After four weeks here he's got everone in town saying, "Hiya, Buddy, Buddy" with a drawl simulating his. [Review of Ned Schuyler's 5 O'Clock Club, Miami Beach, Fla., "Billboard," Nov. 12, 1949]
Buddy system attested from 1920.
buddy (v.): 1931, perhaps originally U.S. underworld slang, usually with up, from buddy (n.). Related: Buddied; buddying.
budge (v.): 1580s, from Middle French bougier "to move, stir" (Modern French bouger), from Vulgar Latin *bullicare "to bubble, boil" (hence, "to be in motion"), from Latin bullire "to boil" (see boil (v.)). Cf. Spanish bullir "to move about, bustle;" Portuguese bulir "to move a thing from its place." Related: Budged; budging.
budgerigar (n.): 1847, from Native Australian, said to mean "good cockatoo," from budgeri "good" + gar "cockatoo."
budget (v.): "to include in a (fiscal) budget," 1884, from budget (n.). Related: Budgeted; budgeting.
budget (n.): early 15c., "leather pouch," from Middle French bougette, diminutive of Old French bouge "leather bag, wallet, pouch," from Latin bulga "leather bag," of Gaulish origin (cf. Old Irish bolg "bag," Breton bolc'h "flax pod"), from PIE *bhelgh- (see belly (n.)). Modern financial meaning (1733) is from notion of treasury minister keeping his fiscal plans in a wallet. Another 18c. transferred sense was "bundle of news," hence the use of the word as the title of some newspapers.
budgie (n.): 1936, short for budgerigar.
buff (n.): 1570s, buffe leather "leather made of buffalo hide," from Middle French buffle "buffalo" (15c., via Italian, from Latin bufalus; see buffalo (n.)).

The color term comes from the hue of buffalo hides (later ox hides). Association of "hide" and "skin" led c.1600 to in the buff. Buff-colored uniforms of New York City volunteer firefighters since 1820s led to meaning "enthusiast" (1903).
The Buffs are men and boys whose love of fires, fire-fighting and firemen is a predominant characteristic. [N.Y. "Sun," Feb. 4, 1903]
buff (adj.): "well-built, hunky," 1980s, from buff (v.) "polish, make attractive."
buff (v.): "to polish, make attractive," 1885, in reference to the treatment of buff leather or else to the use of buff cloth in polishing metals, from buff (n.). Related: Buffed; buffing.
buffalo (n.): 1580s (earlier buffel, 1510s, from Middle French), from Portuguese bufalo "water buffalo," from Latin bufalus, variant of bubalus "wild ox," from Greek boubalos "buffalo," originally a kind of African antelope, later used of a type of domesticated ox in southern Asia and the Mediterranean lands, perhaps from bous "ox, cow" (see cow (n.)). Wrongly applied since 1630s to the American bison. Buffalo gnat is recorded from 1822.
Buffalo: city in western New York state, U.S., of disputed origin (there never were buffalo thereabouts), perhaps from the name of a native chief, or a corruption of French beau fleuve "beautiful river." Buffalo wings finger food so called because the recipe was invented in Buffalo (1964, at Frank & Teressa's Anchor Bar on Main Street).
buffalo (v.): "alarm, overawe," 1900, from buffalo (n.). Probably from the animals' tendency to mass panic. Related: Buffaloed; buffaloing.
buffer (n.): 1835, agent noun from obsolete verb buff "make a dull sound when struck" (mid-16c.), from Old French bufe "a blow, slap, punch" (see buffet (n.2)); hence also "something that absorbs a blow."
buffer (v.): 1894, from buffer (n.). Related: Buffered; buffering.
buffet (v.): c.1200, "to strike with the fist or hand; cuff, box, slap; from Old French bufeter "to strike, slap, punch," from bufet (see buffet (n.2)). Related: Buffeted; buffeting.
buffet (n.1): "table," 1718, from French bufet "bench, stool, sideboard," 12c., of uncertain origin. Sense in English extended 1888 to "meal served from a buffet."
buffet (n.2): c.1200, "blow struck with a fist or weapon," from Old French bufet "slap, punch," diminutive of bufe "a blow, slap, punch; puff of wind," figuratively "cunning trick," probably echoic of the sound of something soft being hit.
bufflehead (n.): small North American duck, 1858 (buffle-headed duck attested from 1831), from buffle (1510s), obsolete variant of buffalo (n.) + head (n.). So called for its large head; earlier the noun meant "stupid person" (1650s; cf. also buffle-headed "big-headed," also "foolish," 1650s).
buffoon (n.): 1540s, "type of pantomime dance;" 1580s, "clown," from Middle French bouffon (16c.), from Italian buffone "jester," from buffa "joke, jest, pleasantry," from buffare "to puff out the cheeks," a comic gesture, of echoic origin. Also cf. -oon.
buffoonery (n.): 1620s; see buffoon + -ery.
Bufo (n.): toad genus, from Latin bufo "a toad," an Osco-Umbrian loan-word, perhaps from PIE *gwebh-, a root denoting sliminess and also forming words for "frog" (cf. Old Prussian gabawo "toad," Old Church Slavonic žaba "frog," Middle Low German kwappe "tadpole," German Quappe).
bug (v.2): "to annoy, irritate," 1949, probably from bug (n.) and a reference to insect pests. Sense of "equip with a concealed microphone" is from 1919. Related: Bugged; bugging.
bug (n.): "insect," 1620s (earliest reference is to bedbugs), of unknown origin, probably but not certainly from or influenced by Middle English bugge "something frightening, scarecrow" (late 14c.), a meaning obsolete since the "insect" sense arose except in bugbear (1570s) and bugaboo (q.v.).

Probably connected with Scottish bogill "goblin, bugbear," or obsolete Welsh bwg "ghost, goblin" (cf. Welsh bwgwl "threat," earlier "fear," Middle Irish bocanách "supernatural being"). Some speculate that these words are from a root meaning "goat" (see buck (n.1)) and represent originally a goat-like spectre. Cf. also bogey (n.1) and German bögge, böggel-mann "goblin." Perhaps influenced in meaning by Old English -budda used in compounds for "beetle" (cf. Low German budde "louse, grub," Middle Low German buddech "thick, swollen").
In the United States bug is not confined, as in England, to the domestic pest, but is applied to all insects of the Coleoptera order, which includes what in this country are generally called beetles. [Farmer & Henley, "Dictionary of Slang and Colloquial English," 1912 abridged edition]
Meaning "defect in a machine" (1889) may have been coined c.1878 by Thomas Edison (perhaps with the notion of an insect getting into the works). Meaning "person obsessed by an idea" (e.g. firebug) is from 1841, perhaps from notion of persistence. Sense of "microbe, germ" is from 1919. Bugs "crazy" is from c.1900. Bug juice as a slang name for drink is from 1869, originally "bad whiskey." The 1811 slang dictionary has bug-hunter "an upholsterer." Bug-word "word or words meant to irritate and vex" is from 1560s.
bug (v.1): "to bulge, protrude," 1872, originally of eyes, perhaps from a humorous or dialect mispronunciation of bulge (v.). Related: Bugged; bugging. As an adjective, bug-eyed recorded from 1872; so commonly used of space creatures in mid-20c. science fiction that the initialism BEM for bug-eyed monster was current by 1953.
bug (v.3): "to scram, skedaddle," 1953, of uncertain origin, perhaps related to bug (v.2), and cf. bug off.
bug off (v.): by 1956, perhaps from bugger off (see bugger (v.)), which chiefly is British (by 1920s) but was picked up in U.S. Air Force slang in the Korean War.
bugaboo (n.): 1843, earlier buggybow (1740), probably an alteration of bugbear (also see bug (n.)), but connected by Chapman ["Dictionary of American Slang"] with Bugibu, demon in the Old French poem "Aliscans" from 1141, which is perhaps of Celtic origin (cf. Cornish bucca-boo, from bucca "bogle, goblin").
bugbear (n.): 1580s, a sort of demon in the form of a bear that eats small children, also "object of dread" (whether real or not), from obsolete bug "goblin, scarecrow" (see bug (n.)) + bear (n.).
bugger (n.): "sodomite," 1550s, earlier "heretic" (mid-14c.), from Medieval Latin Bulgarus "a Bulgarian" (see Bulgaria), so called from bigoted notions of the sex lives of Eastern Orthodox Christians or of the sect of heretics that was prominent there 11c. Cf. Old French bougre "Bulgarian," also "heretic; sodomite." Softened secondary sense of "fellow, chap," is in British English from mid-19c. Related: Buggerly.
bugger (v.): to commit buggery," 1590s, from bugger (n.). Meaning "ruin, spoil" is from 1923. Related: Buggered; buggering.
buggery (n.): mid-14c., "heresy," later "unnatural intercourse" with man or beast, "carnalis copula contra Naturam, & hoc vel per confusionem Specierum". See bugger (n.) + -y (1).
buggy (n.): "light carriage," 1773, of unknown origin. Extended to baby carriages by 1890.
buggy (adj.): "infested with bugs," 1774, from bug (n.) + -y (2).
bughouse: 1902 (n.) "insane asylum;" 1891 (adj.) "insane," from bug (n.) + house (n.); perhaps originally tramps' slang.
bugle (n.): mid-14c., abbreviation of buglehorn "musical horn, hunting horn" (c.1300), from Old French bugle "(musical) horn," also "wild ox, buffalo," from Latin buculus "heifer, young ox," diminutive of bos "ox, cow" (see cow (n.)). Middle English also had the word in the "buffalo" sense and it survived in dialect with meaning "young bull." Modern French bugle is a 19c. borrowing from English.
bugle (v.): 1852, from bugle (n.). Related: Bugled; bugling (1847). Also cf. bugler.
bugler (n.): 1793; see bugle (n.). Bugle-boy attested from 1817.
bugloss (n.): 1530s, from French buglosse, from Latin buglossa, from Greek bouglossos, literally "ox-tongued," from bous "ox" (see cow (n.)) + glossa "tongue" (see gloss (n.2)) . So called from the shape of its leaves.
build (v.): late Old English byldan "construct a house," verb form of bold "house," from Proto-Germanic *buthlam (cf. Old Saxon bodl, Old Frisian bodel "building, house"), from PIE *bhu- "to dwell," from root *bheue- "to be, exist, grow" (see be). Rare in Old English; in Middle English it won out over more common Old English timbran (see timber). Modern spelling is unexplained. Figurative use from mid-15c. Of physical things other than buildings from late 16c. Related: Builded (archaic); built; building.
In the United States, this verb is used with much more latitude than in England. There, as Fennimore Cooper puts it, everything is BUILT. The priest BUILDS up a flock; the speculator a fortune; the lawyer a reputation; the landlord a town; and the tailor, as in England, BUILDS up a suit of clothes. A fire is BUILT instead of made, and the expression is even extended to individuals, to be BUILT being used with the meaning of formed. [Farmer, "Slang and Its Analogues," 1890]
build (n.): "style of construction," 1660s, from build (v.). Earlier in this sense was built (1610s). Meaning "physical construction and fitness of a person" attested by 1981. Earliest sense, now obsolete, was "a building" (early 14c.).
build-up (n.): also buildup, 1927, "accumulation of positive publicity," from build (v.) + up (adv.). Of any accumulation (but especially military) from 1943.