Online Etymology Dictionary

blather (v.): 1520s, Scottish, probably from a Scandinavian source such as Old Norse blaðra "mutter, wag the tongue," perhaps of imitative origin. Related: Blathered; blathering.
blather (n.): 1787, from blather (v.).
blatherskite (n.): c. 1650, bletherskate, in Scottish song "Maggie Lauder," which was popular with soldiers in the Continental Army in the American Revolution, hence the colloquial U.S. use for "talkative fellow, foolish talk," especially in early 19c. From blather (v.) + dialectal skite "contemptible person."
blaxploitation (n.): 1972, from black + exploitation.
blaze (n.1): "bright flame, fire," Old English blæse "a torch, flame, firebrand, lamp," from Proto-Germanic *blas- "shining, white" (source also of Old Saxon blas "white, whitish," Middle High German blas "bald," originally "white, shining," Old High German blas-ros "horse with a white spot," Middle Dutch and Dutch bles, German Blesse "white spot," blass "pale, whitish"), from PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)).
blaze (n.2): "light-colored mark or spot," 1630s, northern English dialect, probably from Old Norse blesi "white spot on a horse's face" (from the same root as blaze (n.1)). A Low German cognate of the Norse word also has been suggested as the source. Applied 1660s in American English to marks cut on tree trunks to indicate a track; thus the verb meaning "to mark a trail;" first recorded 1750, American English. Related: Blazed; blazing.
blaze (v.2): "make public" (often in a bad sense, boastfully), late 14c., perhaps from Middle Dutch blasen "to blow" (on a trumpet), from Proto-Germanic *blaes-an (source also of German blasen, Gothic -blesan), from PIE *bhle-, variant of root *bhel- (2) "to blow, inflate, swell" (see bole).
blaze (v.1): "to burn brightly or vigorously," c. 1200, from blaze (n.1). Related: Blazed; blazing.
blaze (v.3): "to mark" (a tree, a trail), 1750, American English; see blaze (n.2).
blazer (n.): "bright-colored jacket," 1880, British university slang, from blaze (n.1), in reference to the red flannel jackets worn by the Lady Margaret, St. John College, Cambridge, boating club. Earlier it had been used in American English in the sense "something which attracts attention" (1845).
blazes (n.): euphemism for "Hell," 1818, plural of blaze (n.1).
blazing (adj.): late 14c., "shining," also "vehement," present participle adjective from blaze (v.1). As a mild or euphemistic epithet, attested from 1888 (no doubt connected with the blazes in colloquial sense of "Hell").
blazon (n.): "coat of arms," late 13c., from Old French blason (12c.) "a shield, blazon," also "collar bone;" common Romanic (compare Spanish blason, Italian blasone, Portuguese brasao, Provençal blezo, the first two said to be French loan-words); of uncertain origin. OED doubts, on grounds of sense, the connection proposed by 19c. French etymologists to Germanic words related to English blaze (n.1).
blazon (v.): 1560s, "to depict or paint (armorial bearings)," from blazon (n.) or else from French blasonner. Earlier as "to set forth decriptively" (1510s); especially "to vaunt or boast" (1530s), in this use probably from or influenced by blaze (v.2).
bleach (v.): Old English blæcan "bleach, whiten," from Proto-Germanic *blaikjan "to make white" (source also of Old Saxon blek, Old Norse bleikr, Dutch bleek, Old High German bleih, German bleich "pale;" Old Norse bleikja, Dutch bleken, German bleichen "to bleach"), from PIE root *bhel- (1) "to shine, flash, burn" (source also of Sanskrit bhrajate "shines;" Greek phlegein "to burn;" Latin flamma "flame," fulmen "lightning," fulgere "to shine, flash," flagrare "to burn;" Old Church Slavonic belu "white;" Lithuanian balnas "pale").

The same root probably produced black; perhaps because both black and white are colorless, or because both are associated with burning. Compare Old English scimian, related to the source of shine (n.), meaning both "to shine" and "to dim, grow dusky, grow dark." Related: Bleached; bleaching.
bleach (n.): "act of bleaching," 1887; "a bleaching agent," 1898, probably directly from bleach (v.). The Old English noun blæce meant "leprosy;" Late Old English also had blæco "paleness," and Middle English had blech "whitening or bleaching agent."
bleacher (n.): 1540s, "one who bleaches," agent noun from bleach (v.). The "bench for spectators at a sports field" sense (usually bleachers) is attested since 1889, American English; so named because the boards were bleached by the sun.
bleak (adj.): c. 1300, "pale," from Old Norse bleikr "pale, whitish, blond," from Proto-Germanic *blaika- "shining, white," from PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)). Later "bare, windswept" (1530s). Sense of "cheerless" is c. 1719 figurative extension. The same Germanic root produced Old English blac "pale," but this died out, probably from confusion with blæc "black;" however bleak persisted, with a sense of "bare" as well as "pale."
bleakly (adv.): 1530s, from bleak (adj.) + -ly (2).
bleakness (n.): c. 1600, from bleak + -ness.
blear (adj.): c. 1300, blere "watery, rheumy," perhaps related to blur. Compare Middle High German blerre "having blurred vision."
blear (v.): "to dim (of vision); to have watery or rheumy eyes," early 14c., of uncertain origin, possibly from an Old English *blerian, from the same source as blear (adj.). Related: Bleared; blearing.
bleary (adj.): late 14c., from blear + -y (2). Related: Blearily; bleariness.
bleat (v.): Old English blætan, from West Germanic *bhle- (source also of Dutch blaten "to bleat"), of imitative origin (compare Greek blekhe "a bleating; the wailing of children," Old Church Slavonic blejat "to bleat," Latin flere "to weep"). Related: Bleated; bleating.
bleat (n.): c. 1500, from bleat (v.).
bleb (n.): c. 1600, "blister or swelling," imitative. Also used for "bubble" (1640s), "protuberance on a cell surface" (1962).
bled: past tense and past participle of bleed (v.).
bleed (v.): Old English bledan "to let blood," in Middle English and after, "to let blood from surgically;" also "to emit blood," from Proto-Germanic *blodjan "emit blood" (source also of Old Norse blæða, German bluten), from *bhlo-to- "swell, gush, spurt" (see blood (n.)). Meaning "extort money from" is from 1670s. Of dyes or paints, from 1862. Related: Bled; bleeding.
bleeder (n.): 1756, "one who lets blood," agent noun from bleed (v.). As "one with hemophilia," from 1803.
bleeding (n.): late 14c., "a flowing out of blood;" mid-15c. as "a drawing out of blood;" verbal noun formed after earlier present participle adjective (early 13c.) of bleed. Figurative use is from 1796. As a euphemism for bloody, from 1858. In U.S. history, Bleeding Kansas, in reference to the slavery disputes in that territory 1854-60, is attested from 1856, said to have been first used by the New York "Tribune."
bleeding heart (n.): type of flowering plant, so called from 1690s. In the sense of "person excessively sympathetic" (especially toward those the speaker deems not to deserve it) is attested by 1951, but said by many to have been popularized with reference to liberals (especially Eleanor Roosevelt) in 1930s by newspaper columnist Westbrook Pegler (1894-1969), though quotations are wanting; bleeding in a figurative sense of "generous" is from late 16c., and the notion of one's heart bleeding as a figure of emotional anguish is from late 14c., but the exact image here may be the "bleeding heart of Jesus."
bleep (n.): "electronic noise," 1953, imitative.
bleep (v.): 1957, from bleep (n.); specific sense of "edit a sound over a word deemed unfit for broadcast" is from 1968 (earliest reference seems to be to the "Smothers Brothers Comedy Hour" on U.S. television). Related: Bleeped; bleeping.
blemish (v.): early 14c., "to hurt, damage," from Old French blemiss- "to turn pale," extended stem of blemir, blesmir "to make pale; stain, discolor," also "to injure" (13c., Modern French blêmir), probably from Frankish *blesmjan "to cause to turn pale," or some other Germanic source, from Proto-Germanic *blas "shining, white," from PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)).

The order of appearance of senses in Middle English is "hurt, damage;" "impair morally, sully" (late 14c.); "mar, spoil, injure" (early 15c.); "to mar the beauty or soundness of" (mid-15c.). Related: Blemished; blemishing.
blemish (n.): 1520s, from blemish (v.).
blench (v.): Old English blencan "deceive, cheat," from Proto-Germanic *blenk- "to shine, dazzle, blind," from PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.)). Sense of "move suddenly, wince, dodge" is from c. 1300. Related: Blenched; blenching.
blend (v.): c. 1300, blenden, "to mix, mingle, stir up a liquid," in northern writers, from or akin to rare Old English blandan "to mix," blondan (Mercian) or Old Norse blanda "to mix," or a combination of the two; from Proto-Germanic *blandan "to mix," which comes via a notion of "to make cloudy" from an extended Germanic form of the PIE root *bhel- (1) "to shine, flash, burn" (see bleach (v.); also blind (adj.)). Compare Old Saxon and Old High German blantan, Gothic blandan, Middle High German blenden "to mix;" German Blendling "bastard, mongrel," and outside Germanic, Lithuanian blandus "troubled, turbid, thick;" Old Church Slavonic blesti "to go astray." Figurative use from early 14c. Related: Blended; blending.
blend (n.): "mixture formed by blending," 1690s, from blend (v.).
blende (n.): an ore of zinc, 1680s, from German Blende, a back-formation from blenden "to blind, deceive" (see blind (adj.)). So called because it resembles lead but does not yield any.
blender (n.): person or thing that blends, 1872, agent noun from blend (v.). As a type of electric-powered food processor, from 1942.
blenny (n.): 1774, from Latin blennius (in Pliny), from Greek blennos, from blenna "slime, mucus," from PIE *mled-sno-, from root *mel- "soft." The fish so called from the coating on its scales.
blepharoplasty (n.): 1839, from blepharo-, comb. form of Greek blepharon "eyelid" (related to blepein "to look, see") + -plasty.
bless (v.): Old English bletsian, bledsian, Northumbrian bloedsian "to consecrate, make holy, give thanks," from Proto-Germanic *blodison "hallow with blood, mark with blood," from *blotham "blood" (see blood (n.)). Originally a blood sprinkling on pagan altars. This word was chosen in Old English bibles to translate Latin benedicere and Greek eulogein, both of which have a ground sense of "to speak well of, to praise," but were used in Scripture to translate Hebrew brk "to bend (the knee), worship, praise, invoke blessings." L.R. Palmer ("The Latin Language") writes, "There is nothing surprising in the semantic development of a word denoting originally a special ritual act into the more generalized meanings to 'sacrifice,' 'worship,' 'bless,'" and compares Latin immolare (see immolate). Meaning shifted in late Old English toward "pronounce or make happy," by resemblance to unrelated bliss. No cognates in other languages. Related: Blessed; blessing.
blessed (adj.): late 12c., "supremely happy," also "consecrated" (c. 1200), past participle adjective from bless (v.). Reversed or ironic sense of "cursed, damned" is recorded from 1806. Related: Blessedly; blessedness.
blessing (n.): Old English bletsunga, bledsunge; see bless. Meaning "gift from God" is from mid-14c. In sense of "religious invocation before a meal" it is recorded from 1738. Phrase blessing in disguise is recorded from 1746.
blest: alternative past tense and past participle of bless.
bleu: French form of blue (1), used from c. 1890 in names of various French blue cheeses (French fromage bleu) marketed in Britain and U.S.
blew: Old English bleow, past tense of blow (v.1).
blight (n.): 1610s, origin obscure; according to OED it emerged into literary speech from the talk of gardeners and farmers, perhaps ultimately from Old English blæce, blæcðu, a scrofulous skin condition and/or from Old Norse blikna "become pale." Used in a general way of agricultural diseases, sometimes with suggestion of "invisible baleful influence;" hence figurative sense of "anything which withers hopes or prospects or checks prosperity" (1828). Compare slang blighter. Urban blight attested by 1935.
blight (v.): "afflict with blight," 1660s (implied in blighted), from blight (n.). Figurative use by 1712. Related: Blighted; blighting.