Online Etymology Dictionary

brawny (adj.): 1590s, "characterized by muscle," from brawn + -y (2).
bray (v.): c. 1300, from Old French braire "to cry," from Gallo-Roman *bragire "to cry out," perhaps from a Celtic source (compare Gaelic braigh "to shriek, crackle"), probably imitative. Related: Brayed; braying.
bray (n.): c. 1300, from bray (v.).
braze (v.1): "to expose to the action of fire," 1580s, perhaps from French braser "to solder," in Old French, "to burn," related to brese "embers" (see braise). Related: Brazed; brazing.
braze (v.2): "to make of or cover in brass," Old English brasian "to do work in brass, make of brass," from bræs (see brass). Compare glaze from glass.
brazen (adj.): Old English bræsen "of brass," from bræs "brass" (see brass) + -en (2). The figurative sense of "hardened in effrontery" is 1570s (in brazen-face), perhaps suggesting a face unable to show shame (see brass). To brazen it out "face impudently" is from 1550s.
brazier (n.): "metal container to hold burning coals," 1680s, from French brasier "pan of hot coals," from Old French brasier, from brese "embers" (see braise).
Brazil: 1550s, from Spanish/Portuguese terra de brasil "red-dye-wood land," from Spanish brasil or Italian brasile, probably connected to French braize (see braize) for resemblance of color to a glowing ember (but Old Italian form verzino suggests a possible connection with Arabic wars "saffron"). Originally the name of a type of wood from an East Indian tree, used in making dye; the name later was transferred to a similar South American species. Brazil in reference to the wood is attested in English from late 14c. Complicating matters is Hy Brasil, a name applied by 1436 to one of the larger Azores Islands, later transferred to a legendary island or rock off the west coast of Ireland (sighted in 1791 at lat. 51° 10', long. 15° 58').
Brazzaville: capital of Republic of Congo, named for French explorer Pierre Savorgnan de Brazza (1852-1905), who founded it in 1883. An Italian count, his title is from the Adriatic island of Brazza, now Brač in Croatia.
brb: by 1996, Internet chat acronym for be right back.
breach (n.): Old English bryce "breach, fracture, a breaking," from brecan (see break), influenced by Old French breche "breach, opening, gap," from Frankish; both from Proto-Germanic *brecho, *bræko "broken," from PIE root *bhreg- "to break" (see fraction). Figurative sense of "a breaking of rules, etc." was in Old English Breach of contract is at least from 1660s.
breach (v.): 1570s, from breach (n.). Related: Breached; breaching.
bread (n.): Old English bread "bit, crumb, morsel; bread," cognate with Old Norse brauð, Danish brød, Old Frisian brad, Middle Dutch brot, Dutch brood, German Brot. According to one theory [Watkins, etc.] from Proto-Germanic *brautham, which would be from the root of brew (v.) and refer to the leavening.

But OED argues at some length for the basic sense being not "cooked food" but "piece of food," and the Old English word deriving from a Proto-Germanic *braudsmon- "fragments, bits" (cognate with Old High German brosma "crumb," Old English breotan "to break in pieces") and being related to the root of break (v.). It cites Slovenian kruh "bread," literally "a piece."

Either way, by c. 1200 it had replaced the usual Old English word for "bread," which was hlaf (see loaf (n.)). Slang meaning "money" dates from 1940s, but compare breadwinner. Bread-and-butter in the figurative sense of "basic needs" is from 1732. Bread and circuses (1914) is from Latin, in reference to food and entertainment provided by governments to keep the populace happy. "Duas tantum res anxius optat, Panem et circenses" [Juvenal, Sat. x.80].
bread (v.): "to dress with bread crumbs," 1727, from bread (n.). Related: Breaded; breading.
bread-basket (n.): 1550s, "basket for holding bread," from bread (n.) + basket. Slang meaning "stomach" is attested from 1753, especially in pugilism.
breadth (n.): 1520s, alteration of brede "breadth," from Old English brædu "breadth, width, extent," from bræd; probably by analogy of long/length.
breadwinner (n.): also bread-winner, "one who supplies a living for others, especially a family," 1821, from the noun bread (probably in a literal sense) + winner, from win (v.) in its sense of "struggle for, work at." Attested slightly earlier (1818) in sense "skill or art by which one makes a living." Not too far removed from the image at the root of lord (n.).
break (n.): c. 1300, "act of breaking," from break (v.). Sense of "short interval between spells of work" (originally between lessons at school) is from 1861. Meaning "stroke of luck" is attested by 1911, probably an image from billiards (where the break that starts the game is attested from 1865). Meaning "stroke of mercy" is from 1914. Musical sense, "improvised passage, solo" is attested from 1920s in jazz.
break (v.): Old English brecan "to break, shatter, burst; injure, violate, destroy, curtail; break into, rush into; burst forth, spring out; subdue, tame" (class IV strong verb; past tense bræc, past participle brocen), from Proto-Germanic *brekan (source also of Old Frisian breka, Dutch breken, Old High German brehhan, German brechen, Gothic brikan), from PIE root *bhreg- "to break" (see fraction). Most modern senses were in Old English. In reference to the heart from early 13c. Meaning "to disclose" is from early 13c.

Break bread "share food" (with) is from late 14c. Break the ice is c. 1600, in reference to the "coldness" of encounters of strangers. Break wind first attested 1550s. To break (something) out (1890s) probably is an image from dock work, of freeing cargo before unloading it. The ironic theatrical good luck formula break a leg (by 1948, said to be from at least 1920s) has parallels in German Hals- und Beinbruch "break your neck and leg," and Italian in bocca al lupo. Evidence of a highly superstitious craft (see Macbeth). According to Farmer & Henley, in 17c. the expression was used euphemistically, of a woman, "to have a bastard."
break dancing (n.): 1982, but the style itself evolved late 1970s in South Bronx. The reference is to the rhythmic break in a pop-dance song (see break (n.)), which the DJs isolated and the dancers performed to. Breakdown "a riotous dance, in the style of the negroes" is recorded from 1864.
breakable (adj.): 1560s, from break (v.) + -able. As a noun, breakables is attested from 1820.
breakage (n.): 1813, "action of breaking," from break (v.) + -age. Meaning "loss or damage done by breaking" is from 1848.
breakaway: 1906 (n.), in reference to sports; 1930s (adj.) in reference to splinter groups; from break (v.) + away (adv.).
breakdown (n.): "a collapse," 1832, from break (v.) + down (adv.). The verbal phrase is attested from late 14c. The noun, specifically of machinery, is from 1838; meaning "an analysis in detail" is from 1936. Nervous breakdown is from 1905.
breaker (n.): "heavy ocean wave," 1680s, agent noun from break (v.). Related: Breakers.
breakeven (adj.): also break-even; usually with point, 1938, from break (v.) + even (adv.). The verbal phrase in the financial sense is recorded from 1914.
breakfast (n.): mid-15c., from break (v.) + fast (n.). For vowel shift, see met (v.). An Old English word for it was undernmete (see undern), also morgenmete "morning meal.". The verb is recorded from 1670s. Related: Breakfasted; breakfasting.

Spanish almuerzo "lunch," but formerly and still locally "breakfast," is from Latin admorsus, past participle of admordere "to bite into," from ad- "to" + mordere "to bite." In common with almuerzo, words for "breakfast" tend over time to shift in meaning toward "lunch;" compare French déjeuner "breakfast," later "lunch" (equivalent of Spanish desayuno "breakfast"), both from Vulgar Latin *disieiunare "to breakfast," from Latin dis- "apart, in a different direction from" + ieiunare, jejunare "fast" (see jejune; also compare dine). German Frühstück is from Middle High German vruostücke, literally "early bit."
breakneck (adj.): 1560s, "likely to end in a broken neck," from break (v.) + neck (n.).
breakout (n.): 1820, from break (v.) + out (adv.). The verbal phrase goes back to Old English ut brecan, utabrecan. Transitive sense is attested from 1610s.
breakthrough (n.): 1918, in a military sense, from break (v.) + through (adv.). The verbal phrase is attested from c. 1400. Meaning "abrupt solution or progress" is from 1930s, on the notion of a successful attack.
breakup (n.): also break-up, 1795, from verbal expression break up (mid-15c.), which was used originally of plowland, later of groups, assemblies, etc. Of things (also of marriages, relationships), "to disintegrate," from mid-18c. See break (v.) + up (adv.). Break it up as a command to stop a fight, etc., is recorded from 1936.
breakwater (n.): 1721, from break (v.) + water (n.1).
bream (n.): freshwater fish, late 14c., from Old French braisme "bream," from Frankish *brahsima, from West Germanic *brahsm- (compare Old High German brahsima), perhaps from Proto-Germanic base *brehwan "to shine, glitter, sparkle," from PIE *bherek- (see braid (v.)).
breast (n.): Old English breost "breast, bosom; mind, thought, disposition," from Proto-Germanic *breustam "breast" (source also of Old Saxon briost, Old Frisian briast, Old Norse brjost, Dutch borst, German brust, Gothic brusts), perhaps literally "swelling" and from PIE root *bhreus- "to swell, sprout" (source also of Middle Irish bruasach "having a broad, strong chest," Old Irish bruinne "breast"). The spelling conforms to the Scottish and northern England dialectal pronunciation. Figurative sense of "seat of the emotions" was in Old English.
breastbone (n.): "sternum," Old English breostban; see breast (n.) + bone (n.).
breastwork (n.): "fieldwork thrown up breast-high for defense," 1640s, from breast (n.) + work (n.) in "fortification" sense. Old English had breostweall in same sense.
breath (n.): Old English bræð "odor, scent, stink, exhalation, vapor" (Old English word for "air exhaled from the lungs" was æðm), from Proto-Germanic *bræthaz "smell, exhalation" (source also of Old High German bradam, German Brodem "breath, steam"), from PIE root *gwhre- "to breathe, smell."
breathalyzer (n.): 1960, from breath + (an)alyzer; an earlier name for it was drunkometer (1934).
breathe (v.): c. 1300, not in Old English, but it retains the original Old English vowel of its source word, breath. Related: Breathed; breathing.
breather (n.): c. 1600, "a living creature, one who breathes," agent noun from breathe. Meaning "spell of exercise to stimulate breathing" is from 1836; that of "a rest to recover breath" is from 1901.
breathless (adj.): late 14c., "unable to breathe," from breath + -less. Meaning "out of breath, panting" is from mid-15c. Used from 1590s in the sense "dead." Meaning "forgetting to breathe due to excitement, awe, anticipation, etc." is recorded from 1802. Related: Breathlessly; breathlessness.
breathtaking (adj.): 1867, from breath + present participle of take (v.). Phrase to take (one's) breath away with astonishment or delight is from 1864. Breathtaking (n.) "act of taking breaths or a breath" is from 1620s. Related: Breathtakingly.
breathy (adj.): 1520s, "pertaining to breath," from breath + -y (2). Of voices, "full of breath," from 1883. Related: Breathily; breathiness.
breccia (n.): "rock of angular pieces," 1774, from Italian breccia, "marble of angular pieces," from a Germanic source akin to Old High German brecha "a breaking," from Proto-Germanic *brekan, from PIE *bhreg- "to break" (see fraction).
bred (adj.): from past tense and past participle of breed (v.).
breech (n.): "back part of a gun or firearm," 1570s, from singular of breeches (q.v.).
breeches (n.): c. 1200, a double plural, from Old English brec "breeches," which already was plural of broc "garment for the legs and trunk," from Proto-Germanic *brokiz (source also of Old Norse brok, Dutch broek, Danish brog, Old High German bruoh, German Bruch, obsolete since 18c. except in Swiss dialect), perhaps from PIE root *bhreg- (see break (v.)). The Proto-Germanic word is a parallel form to Celtic *bracca, source (via Gaulish) of Latin braca (aource of French braies), and some propose that the Germanic word group is borrowed from Gallo-Latin, others that the Celtic was from Germanic.

Expanded sense of "part of the body covered by breeches, posterior" led to senses in childbirthing (1670s) and gunnery ("the part of a firearm behind the bore," 1570s). As the popular word for "trousers" in English, displaced in U.S. c. 1840 by pants. The Breeches Bible (Geneva Bible of 1560) so called on account of rendition of Gen. iii:7 (already in Wyclif) "They sewed figge leaues together, and made themselues breeches."
breed (v.): Old English bredan "bring young to birth, carry," also "cherish, keep warm," from West Germanic *brodjan (source also of Old High German bruoten, German brüten "to brood, hatch"), from *brod- "fetus, hatchling," from PIE *bhreue- "burn, heat" (see brood (n.)). Original notion of the word was incubation, warming to hatch. Sense of "grow up, be reared" (in a clan, etc.) is late 14c. Related: Bred; breeding.
breed (n.): "race, lineage, stock" (originally of animals), 1550s, from breed (v.). Of persons, from 1590s. Meaning "kind, species" is from 1580s.
breeder (n.): 1570s, "one who produces or originates," agent noun from breed (v.). Meaning "one who breeds cattle" or some other animal is recorded from 1530s. Of nuclear reactors, from 1948. As a scornful homosexual term for "heterosexual person," attested from 1986.