Online Etymology Dictionary

bluff (n.2): 1844 as an alternative name for poker; from bluff (v.). As "an act of bluffing" by 1864. Blind man's bluff formerly was called hoodman-blind (1560s).
bluffing (n.): 1845, in the poker sense, verbal noun from bluff (v.).
bluffs (n.): see bluff (n.1).
bluish (adj.): late 14c., blewysh; see blue + -ish.
blunder (v.): mid-14c., "to stumble about blindly," from a Scandinavian source akin to Old Norse blundra "shut one's eyes," from PIE root *bhlendh- (see blind). Meaning "make a stupid mistake" is first recorded 1711. Related: Blundered; blundering.
blunder (n.): mid-14c., apparently from blunder (v.), though of about the same age.
blunderbuss (n.): 1650s, from Dutch donderbus, from donder "thunder" (Middle Dutch doner, donder, from Proto-Germanic *thunaraz; see thunder (n.)) + bus "gun" (originally "box, tube"); altered by resemblance to blunder.
blunderful (adj.): 1881, jocular blend of blunder and wonderful.
blundering: mid-14c. as a present participle adjective; mid-15c. as a verbal noun, from blunder (v.). Related: Blunderingly.
blunt (adj.): c. 1200, "dull, obtuse," perhaps from or related to Old Norse blundra (see blunder (v.)). Of tools or weapons, late 14c. Meaning "abrupt of speech or manner" is from 1580s.
blunt (v.): late 14c., from blunt (adj.). Related: Blunted; blunting.
blunt (n.): street slang for "marijuana and tobacco cigar" (easier to pass around, easier to disguise, and the stimulant in the tobacco enhances the high from the pot) surfaced c. 1993, but is said to have originated among Jamaicans in New York City in the early 1980s; from Phillies Blunt brand cigars; see blunt (adj.), which has been used of certain cigars since 19c.
Users say that the Phillies Blunt brand produces less harsh-tasting or sweeter smoke. The leaf wrapper of a Phillies Blunt is strong enough to hold together through the manipulations of making a blunt. Other brands fall apart. [http://nepenthes.lycaeum.org/Drugs/THC/Smoke/blunts.html]
bluntly (adv.): 1550s, "stupidly," from blunt (adj.) + -ly (2). Meaning "directly" is from 1570s.
bluntness (n.): late 15c., "stupidity," from blunt (adj.) + -ness. Meaning "rudeness" is from c. 1600.
blur (n.): 1540s, "smear on the surface of writing;" perhaps akin to blear. Extended sense of "confused dimness" is from 1860.
blur (v.): 1580s, and thus probably from blur (n.), but the dates are close and either might be the original. Related: Blurred; blurring.
blurb (n.): used by U.S. scholar Brander Matthews (1852-1929) in 1906 in "American Character;" popularized 1907 by U.S. humorist Frank Gelett Burgess (1866-1951). Originally mocking excessive praise printed on book jackets.
Gelett Burgess ... then entertained the guests with some characteristic flashes of Burgessian humor. Referring to the word "blurb" on the wrapper of his book he said: "To 'blurb' is to make a sound like a publisher. The blurb was invented by Frank A. Munsey when he wrote on the front of his magazine in red ink 'I consider this number of Munsey's the hottest pie that ever came out of my bakery.' ... A blurb is a check drawn on Fame, and it is seldom honored.["] ["Publishers' Weekly," May 18, 1907]
blurry (adj.): 1855, from blur + -y (2). Related: Blurrily; blurriness.
blurt (v.): 1570s, probably echoic. Related: blurted; blurting. As a noun, 1570s, probably from the verb.
blush (v.): mid-14c., bluschen, blischen, probably from Old English blyscan "blush, become red, glow" (glossing Latin rutilare), akin to blyse "torch," from Proto-Germanic *blisk- "to shine, burn," which also yielded words in Low German (Dutch blozen "to blush") and Scandinavian (Danish blusse "to blaze; to blush"); ultimately from PIE *bhel- (1) "to shine, flash, burn" (see bleach (v.)).

For vowel evolution, see bury. Earliest recorded senses were "to shine brightly; to look, stare." Sense of "turn red in the face" (with shame, modesty, etc.) is from c. 1400. Related: Blushed; blushing.
blush (n.): mid-14c., "a look, a glance" (sense preserved in at first blush), also "a gleam, a gleaming" (late 14c.), from blush (v.). As "a reddening of the face" from 1590s. Meaning "a rosy color" is 1590s.
bluster (v.): late 14c., from a Low German source, such as Middle Low German blüstren "to blow violently," East Frisian blüstern "to bluster" (see blow (v.1)). Related: Blustered; blustering.
bluster (n.): 1580s, from bluster (v.).
blustery (adj.): 1707, from bluster (n.) + -y (2). Blustering in this sense is recorded from 1510s.
BMX: 1978, semi-acronym from bicycle motocross.
bo tree (n.): 1680s, from Sinhalese bo, from Pali bodhi, short for bodhi-taru "bo tree," literally "tree of wisdom or enlightenment" (related to Sanskrit buddhah "awakened;" see bid) + taru "tree."
boa (n.): late 14c., "large snake," from Latin boa, type of large serpent mentioned in Pliny's "Natural History;" origin unknown (in Middle English folk etymology associated with Greek bous "ox"). Extension to "snake-like coil of fur worn by ladies" is from 1836. The popular name boa constrictor is from 1788.
Boanerges: name given by Christ to his disciples John and James, the two sons of Zebedee (Mark iii:17), Late Latin, from Ecclesiastical Greek Boanerges, from a Galilean dialectal corruption of Hebrew bene reghesh "sons of rage" (interpreted in Greek as "sons of thunder"), from bene (see B'nai B'rith) + reghesh "commotion, tumult, throng." Applied figuratively to zealous or loud preachers.
boar (n.): Old English bar "boar," from Proto-Germanic *bairaz (source also of Old Saxon ber, Dutch beer, Old High German ber "a boar"), which is of unknown origin with no cognates outside West Germanic. Applied in Middle English to persons of boar-like character.
board (n.1): Old English bord "a plank, flat surface," from Proto-Germanic *burdam (source also of Old Norse borð "plank," Dutch bord "board," Gothic fotu-baurd "foot-stool," German Brett "plank"), from PIE *bhrdh- "board," from root *bherdh- "to cut." See also board (n.2), with which this is so confused as practically to form one word (if indeed they were not the same word all along).

A board is thinner than a plank, and generally less than 2.5 inches thick. The transferred meaning "food" (late 14c.) is an extension of the late Old English sense of "table" (compare boarder, boarding); hence, also, above board "honest, open" (1610s). A further extension is to "table where council is held" (1570s), then transferred to "leadership council, council (that meets at a table)," 1610s.
board (n.2): "side of ship," Old English bord "border, rim, ship's side," from Proto-Germanic *bordaz (source also of Old Saxon bord, Dutch boord, German Bord, Old High German bart, Old Norse barð), perhaps from the same source as board (n.1), but not all sources accept this. Connected to border; see also starboard.

If not etymologically related to board (n.1), the two forms represented in English by these words were nonetheless confused at an early date in most Germanic languages, a situation made worse in English because this Germanic root also was adopted as Medieval Latin bordus (source of Italian and Spanish bordo). It also entered Old French as bort "beam, board, plank; side of a ship" (12c., Modern French bord), either from Medieval Latin or Frankish, and from thence it came over with the Normans to mingle with its native cousins. By now the senses are inextricably tangled. Some etymology dictionaries treat them as having been the same word all along.
board (v.): verb senses derived from various senses of board (n.1) and board (n.2) include "come alongside" (a ship), mid-15c. (from n.2); "put boards on, frame with boards," late 14c. (implied in boarded, from n.1); " to get onto" (a ship), 1590s, transferred from mid-19c. to stages, railway cars, aircraft, etc. (from n.2). Meaning "to be supplied with food and lodging" is from 1550s (from n.1 in transferred sense). Transitive meaning "provide with daily meals and lodging" is from 1590s. Related: Boarded; boarding.
boarder (n.): 1520s, "one who has food and/or lodging at the house of another," agent noun from board (v.), in the "be supplied with food" sense; meaning "one who boards (an enemy's) ships" is from 1769, from a verbal sense derived from board (n.2).
boarding (n.): 1530s, "supplying of meals, food and lodging," from board (n.1) in its extended sense of "food" (via notion of "table"). Boarding-school is from 1670s; boarding-house attested from 1728.
boardroom (n.): also board-room, 1731, from board (n.1) in the sense of "table where council is held" + room (n.).
boardwalk (n.): "walkway made of boards," 1864, American English, from board (n.1) + walk (n.). As a seaside attraction from 1881, first in reference to Atlantic City, N.J.
boast (n.): mid-13c., "arrogance, presumption, pride, vanity;" c. 1300, "a brag, boastful speech," from Anglo-French bost "ostentation," probably via Scandinavian (compare Norwegian baus "proud, bold, daring"), from Proto-Germanic *bausia "to blow up, puff up, swell" (source also of Middle High German bus "swelling," dialectal German baustern "to swell;" Middle Dutch bose, Dutch boos "evil, wicked, angry," Old High German bosi "worthless, slanderous," German böse "evil, bad, angry"), from PIE *bhou-, variant of root *beu-, *bheu- "to grow, swell" (see bull (n.2)).

The notion apparently is of being "puffed up" with pride; compare Old English belgan "to become angry, offend, provoke," belg "anger, arrogance," from the same root as bellows and belly (n.). Related: Boasted; boasting. An Old English word for "boasting" was micelsprecende, "big talk."
boast (v.): early 14c., "to brag, speak arrogantly;" from the same source as boast (n.). Related: Boasted; boasting.
boastful (adj.): early 14c., from boast (n.) + -ful. Related: Boastfully; boastfulness.
boat (n.): Old English bat "boat, ship, vessel," from Proto-Germanic *bait- (source also of Old Norse batr, Dutch boot, German Boot), possibly from PIE root *bheid- "to split" (see fissure) if the notion is of making a boat by hollowing out a tree trunk; or it may be an extension of the name for some part of a ship. French bateau "boat" is from Old English or Norse. Spanish batel, Italian battello, Medieval Latin batellus likewise probably are from Germanic.
boatswain (n.): mid-15c., from late Old English batswegen, from bat "boat" (see boat (n.)) + Old Norse sveinn "boy" (see swain). Phonetic spelling bo'sun/bosun is attested from 1840.
BOATSWAIN. The warrant officer who in the old Navy was responsible for all the gear that set the ship in motion and all the tackle that kept her at rest. [Sir Geoffrey Callender, "Sea Passages," 1943]
bob (v.1): "move with a short, jerking motion," late 14c., probably connected to Middle English bobben "to strike, beat" (late 13c.), perhaps of echoic origin. Another early sense was "to make a fool of, cheat" (early 14c.). Related: Bobbed; bobbing. The sense in bobbing for apples (or cherries) recorded by 1799.
bob (n.2): "short hair," 1680s, attested 1570s in sense of "a horse's tail cut short," from earlier bobbe "cluster" (as of leaves), mid-14c., a northern word, perhaps of Celtic origin (compare Irish baban "tassel, cluster," Gaelic babag). Used over the years in various senses connected by the notion of "round, hanging mass," such as "weight at the end of a line" (1650s). The hair sense was revived with a shift in women's styles early 20c. (verb 1918, noun 1920). Related words include bobby pin, bobby sox, bobsled, bobcat.
bob (n.1): "act of bobbing," 1540s, from bob (v.1). As a slang word for "shilling" it is attested from 1789, but the signification is unknown.
bobbin (n.): 1520s, from French bobine, small instrument used in sewing or tapestry-making, perhaps from Latin balbus (see babble (v.)) for the stuttering, stammering noise it made.
bobbinet (n.): 1819, from bobbin + net (n.).
bobble (v.): 1812, frequentative of bob (v.1). The notion is "to move or handle something with continual bobbing." Related: Bobbled; bobbling. Bobble-head as a type of doll is from 1968.
bobby (n.): "London policeman," 1844, from Mr. (later Sir) Robert Peel (1788-1850), Home Secretary who introduced the Metropolitan Police Act (10 Geo IV, c.44) of 1829. Compare peeler.
bobby pin (n.): 1928, from diminutive of bob (n.2) + pin (n.).
bobby sox: 1943, from diminutive of bob (n.2) + sox. So called because they are "shortened" compared to knee-socks. Derivative bobby-soxer first attested 1944.
Months ago colored bobby sox folded at the top were decreed, not by anyone or any group but, as usual, by a sudden mysterious and universal acceptance of the new idea. Now no teen-ager dares wear anything but pure white socks without a fold. ["Life" magazine, Dec. 11, 1944]