bulk (v.) Look up bulk at Dictionary.com
"swell, become more massive," 1550s (usually with up), from bulk (n.). Related: Bulked; bulking.
bulk (n.) Look up bulk at Dictionary.com
mid-15c., "a heap," earlier "ship's cargo" (mid-14c.), from a Scandinavian source akin to Old Norse bulki "a heap; ship's cargo," thus "goods loaded loose" (perhaps literally "rolled-up load"), from Proto-Germanic *bul-, from PIE root *bhel- (2) "to blow, inflate, swell" (see bole).

Meaning extended by confusion with obsolete bouk "belly" (from Old English buc "body, belly," from Proto-Germanic *bukaz; see bucket), which led to sense of "size," first attested mid-15c.
bulkhead (n.) Look up bulkhead at Dictionary.com
late 15c., with head (n.); the first element perhaps from bulk "framework projecting in the front of a shop" (1580s), which is perhaps from Old Norse bolkr "beam, balk" (see balk (n.)).
bulky (adj.) Look up bulky at Dictionary.com
mid-15c., "plump, stout," from bulk (n.) + -y (2). Related: Bulkiness.
bull (v.) Look up bull at Dictionary.com
"push through roughly," 1884, from bull (n.1). Related: Bulled; bulling.
bull (n.3) Look up bull at Dictionary.com
"false talk, fraud," Middle English, apparently from Old French bole "deception, trick, scheming, intrigue," and perhaps connected to modern Icelandic bull "nonsense."
Sais christ to ypocrites ... yee ar ... all ful with wickednes, tresun and bull. ["Cursor Mundi," early 14c.]
There also was a verb bull meaning "to mock, cheat," which dates from 1530s.
bull (n.1) Look up bull at Dictionary.com
"bovine male animal," from Old English bula "a bull, a steer," or Old Norse boli "bull," both from Proto-Germanic *bullon- (source also of Middle Dutch bulle, Dutch bul, German Bulle), perhaps from a Germanic verbal stem meaning "to roar," which survives in some German dialects and perhaps in the first element of boulder (q.v.). The other possibility [Watkins] is that the Germanic root is from PIE *bhln-, from root *bhel- (2) "to blow, inflate, swell" (see bole).

An uncastrated male, reared for breeding, as opposed to a bullock or steer. Extended after 1610s to males of other large animals (elephant, alligator, whale, etc.). Stock market sense is from 1714 (see bear (n.)). Meaning "policeman" attested by 1859. Figurative phrase to take the bull by the horns first recorded 1711. To be a bull in a china shop, figurative of careless and inappropriate use of force, attested from 1812 and was the title of a popular humorous song in 1820s England. Bull-baiting attested from 1570s.
bull (n.2) Look up bull at Dictionary.com
"papal edict," c. 1300, from Medieval Latin bulla "sealed document" (source of Old French bulle, Italian bulla), originally the word for the seal itself, from Latin bulla "round swelling, knob," said ultimately to be from Gaulish, from PIE *beu-, a root supposed to have formed words associated with swelling (source also of Lithuanian bule "buttocks," Middle Dutch puyl "bag," also possibly Latin bucca "cheek").
bull-dyke (n.) Look up bull-dyke at Dictionary.com
also bulldyke, 1926, from bull (n.1) + dyke.
bull-headed (adj.) Look up bull-headed at Dictionary.com
also bullheaded, "obstinate," 1818, from bull (n.1) + head (n.).
bull-ring (n.) Look up bull-ring at Dictionary.com
arena for bull fights, c. 1600, from bull (n.1) + ring (n.1).
bulla (n.) Look up bulla at Dictionary.com
1876, from Latin bulla (plural bullae), literally "bubble" (see bull (n.2)).
bulldog (n.) Look up bulldog at Dictionary.com
c. 1500, from bull (n.1) + dog (n.). Perhaps from shape, perhaps because originally used for baiting bulls.
bulldoze (v.) Look up bulldoze at Dictionary.com
by 1880, from an earlier noun, bulldose "a severe beating or lashing" (1876), literally "a dose fit for a bull," a slang word referring to the intimidation beating of black voters (by either blacks or whites) in the chaotic 1876 U.S. presidential election. See bull (n.1) + dose (n.). Related: Bulldozed; bulldozing.
bulldozer (n.) Look up bulldozer at Dictionary.com
"person who intimidates by violence," 1876, agent noun from bulldoze (q.v.). Meaning extended to ground-clearing caterpillar tractor in 1930.
bullet (n.) Look up bullet at Dictionary.com
1550s, from Middle French boulette "cannonball, small ball," diminutive of boule "a ball" (13c.), from Latin bulla "round thing, knob" (see bull (n.2)). Earliest version of bite the bullet recorded 1891, probably with a sense of giving someone a soft lead bullet to clench in the teeth during a painful operation.
bulletin (n.) Look up bulletin at Dictionary.com
1765, from French bulletin (16c.), modeled on Italian bulletino, diminutive of bulletta "document, voting slip," itself a diminutive of Latin bulla (see bull (n.2)) with equivalent of Old French -elet (see -let). The word was used earlier in English in the Italian form (mid-17c.). Popularized by their use in the Napoleonic Wars as the name for dispatches sent from the front and meant for the home public (which led to the proverbial expression as false as a bulletin). Bulletin board is from 1831.
bullfinch (n.) Look up bullfinch at Dictionary.com
1560s, from bull (n.1) + finch; supposedly so called for the shape of its head and neck; compare French bouvreuil.
bullfrog (n.) Look up bullfrog at Dictionary.com
also bull-frog, 1738, from bull (n.1) + frog (n.1). So called for its voice.
bullied (adj.) Look up bullied at Dictionary.com
1851, past participle adjective from bully (v.).
bullion (n.) Look up bullion at Dictionary.com
early 15c., "uncoined gold or silver," from Anglo-French bullion "bar of precious metal," also "place where coins are made, mint," perhaps, through the notion of "melting," from Old French boillir "to boil," from Latin bullire "boil" (see boil (v.)). But perhaps it is rather from Old French bille "stick, block of wood" (see billiards).
bullish (adj.) Look up bullish at Dictionary.com
1560s, from bull (n.1) + -ish; stock market sense is from 1882. Related: Bullishly; bullishness.
bullock (n.) Look up bullock at Dictionary.com
Old English bulluc "young bull," from Proto-Germanic *bulluka-, from the stem of bull (n.1). Now always a castrated bull reared for beef.
bullpen (n.) Look up bullpen at Dictionary.com
also bull-pen, 1915, in the baseball sense, from bull (n.1) + pen (n.2); perhaps from earlier slang meaning "temporary holding cell for prisoners" (1809). Bullpen also was the name of a baseball-like game played in U.S. late 19c.
bullseye (n.) Look up bullseye at Dictionary.com
also bulls-eye, 1833, "center of a target," from bull (n.1) + eye (n.). So called for size and color. Meaning "shot that hits the mark" is from 1857.
bullshit (n.) Look up bullshit at Dictionary.com
"eloquent and insincere rhetoric," 1915, American English slang; see bull (n.1) + shit (n.), probably because it smells. But bull in the sense of "trivial or false statements" (1914), which usually is associated with this, might be a continuation of Middle English bull "false talk, fraud" (see bull (n.3)).
bullshit (v.) Look up bullshit at Dictionary.com
by 1942, from bullshit (n.). Related: Bullshitted; bullshitting.
bully (v.) Look up bully at Dictionary.com
1710, from bully (n.). Related: Bullied; bullying.
bully (n.) Look up bully at Dictionary.com
1530s, originally "sweetheart," applied to either sex, from Dutch boel "lover; brother," probably a diminutive of Middle Dutch broeder "brother" (compare Middle High German buole "brother," source of German Buhle "lover;" see brother (n.)).

Meaning deteriorated 17c. through "fine fellow" and "blusterer" to "harasser of the weak" (1680s, from bully-ruffian, 1650s). Perhaps this was by influence of bull (n.1), but a connecting sense between "lover" and "ruffian" may be in "protector of a prostitute," which was one sense of bully (though not specifically attested until 1706). "Sweetheart" words often go bad in this way; compare leman, also ladybird, which in Farmer & Henley is "1. A whore; and (2) a term of endearment." The expression meaning "worthy, jolly, admirable" (especially in 1864 U.S. slang bully for you!) is first attested 1680s, and preserves an earlier, positive sense of the word.
bully pulpit (n.) Look up bully pulpit at Dictionary.com
1904, coined by U.S. president Teddy Roosevelt, in reference to the White House.
bullying (n.) Look up bullying at Dictionary.com
1802, verbal noun from bully (v.).
bulrush (n.) Look up bulrush at Dictionary.com
also bullrush, type of tall plant growing in or near water (in Biblical use, the Egyptian papyrus), mid-15c., bolroysche, from rush (n.); the signification of bull is doubtful.
bulwark (n.) Look up bulwark at Dictionary.com
"planking or woodwork round the uppermost parts of a vessel," early 15c., from Middle Dutch bulwerke or Middle High German bolwerc, probably from bole "plank, tree trunk" (from Proto-Germanic *bul-, from PIE root *bhel- (2) "to blow, swell;" see bole) + werc "work" (see work (n.)). Figurative sense "means of defense or security" is from 1570s.
bum (v.) Look up bum at Dictionary.com
1863, "to loaf and beg," American English, a word from the Civil War, perhaps a back-formation from bummer "loafer," or from bum (n.). Meaning "to feel depressed" is from 1973, perhaps from bummer in the "bad experience" sense. Related: Bummed; bumming.
bum (adj.) Look up bum at Dictionary.com
"of poor quality," 1859, American English, from bum (n.). Bum steer in figurative sense of "bad advice" attested from 1901.
bum (n.1) Look up bum at Dictionary.com
"buttocks," late 14c., "probably onomatopœic, to be compared with other words of similar sound and with the general sense of 'protuberance, swelling.' " [OED]
bum (n.2) Look up bum at Dictionary.com
"dissolute loafer, tramp," 1864, American English, from bummer "loafer, idle person" (1855), probably from German slang bummler "loafer," from bummeln "go slowly, waste time." Bum first appears in a German-American context, and bummer was popular in the slang of the North's army in the American Civil War (as many as 216,000 German immigrants in the ranks). Bum's rush "forcible ejection" first recorded 1910.
bumbailiff (n.) Look up bumbailiff at Dictionary.com
server of writs, maker of arrests, etc., c. 1600, from bum "arse" (see bum (n.1)), because he was always felt to be close behind, + bailiff.
bumble (v.) Look up bumble at Dictionary.com
"to flounder, blunder," 1530s, probably of imitative origin. Related: Bumbled; bumbler; bumbling.
Bumble Look up Bumble at Dictionary.com
"self-important petty official," 1856, from the name of the fussy, pompous, stupid beadle in Dickens' "Oliver Twist."
bumblebee (n.) Look up bumblebee at Dictionary.com
also bumble-bee, 1520s, replacing Middle English humbul-be (altered by association with Middle English bombeln "to boom, buzz," late 14c.); echoic, from PIE echoic root *kem "to hum."
bumf (n.) Look up bumf at Dictionary.com
"papers, paperwork," 1889, British schoolboy slang, originally "toilet-paper," from bum-fodder.
bummer (n.) Look up bummer at Dictionary.com
"loafer, idle person," 1855, possibly an extension of the British word for "backside" (similar development took place in Scotland by 1540), but more probably from German slang bummler "loafer," agent noun from bummeln "go slowly, waste time."

According to Kluge, the German word is from 17c., and the earliest sense of it is "oscillate back and forth;" possibly connected to words in German for "dangle" (baumeln), via "back-and-forth motion" of a bell clapper, transferred to "going back and forth," hence "doing nothing." Meaning "bad experience" is 1968 slang.
bump (v.) Look up bump at Dictionary.com
1560s, "to bulge out;" 1610s, "to strike heavily," perhaps from Scandinavian, probably echoic, original sense was "hitting" then of "swelling from being hit." Also has a long association with obsolete bum "to make a booming noise," which perhaps influenced surviving senses such as bumper crop, for something full to the brim (see bumper). To bump into "meet" is from 1880s; to bump off "kill" is 1908 in underworld slang. Related: Bumped; bumping. Bumpsy (adj.) was old slang for "drunk" (1610s).
bump (n.) Look up bump at Dictionary.com
1590s, "protuberance caused by a blow;" 1610s as "a dull, solid blow;" see bump (v.). The dancer's bump and grind attested from 1940.
bumper (n.) Look up bumper at Dictionary.com
1670s, "glass filled to the brim;" perhaps from notion of bumping as "large," or from a related sense of "booming" (see bump (v.)). Meaning "anything unusually large" is from 1759, slang. Agent-noun meaning "buffer of a car" is from 1839, American English, originally in reference to railway cars; 1901 of automobiles (in phrase bumper-to-bumper, in reference to a hypothetical situation; of actual traffic jams by 1908).
bumpkin (n.) Look up bumpkin at Dictionary.com
"awkward country fellow," 1560s, probably from Middle Dutch bommekijn "little barrel," diminutive of boom "tree" (see beam (n.)). Apparently, though itself Dutch, it began as a derogatory reference to Dutch people as short and dumpy.
bumptious (adj.) Look up bumptious at Dictionary.com
"assertive," 1803, probably a humorous coinage from bump on the pattern of fractious, etc. Related: Bumptiously; bumptiousness.
bumpy (adj.) Look up bumpy at Dictionary.com
1865, from bump + -y (2).
Fasten your seatbelts. It's going to be a bumpy night. [Bette Davis ("Margo Channing"), "All About Eve," 1950]
Related: Bumpiness.
bun (n.) Look up bun at Dictionary.com
late 14c., origin obscure, perhaps from Old French buignete "a fritter," originally "boil, swelling," diminutive of buigne "swelling from a blow, bump on the head," from a Germanic source (compare Middle High German bunge "clod, lump"), or from Gaulish *bunia (compare Gaelic bonnach). Spanish buñelo "a fritter" apparently is from the same source. Of hair coiled at the back of the head, first attested 1894. To have a bun in the oven "be pregnant" is from 1951.

The first record of buns in the sense of "male buttocks" is from 1960s, perhaps from a perceived similarity; but bun also meant "tail of a hare" (1530s) in Scottish and northern England dialect and was transferred to human beings (and conveniently rhymed with nun in ribald ballads). This may be an entirely different word; OED points to Gaelic bun "stump, root."