bull (n.1)youdaoicibaDictYouDict[bull 词源字典]
"bovine male animal," from Old English bula "a bull, a steer," or Old Norse boli "bull," both from Proto-Germanic *bullon- (cognates: 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 etymology, bull origin, 英语词源]
bull (n.2)youdaoicibaDictYouDict
"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 (cognates: Lithuanian bule "buttocks," Middle Dutch puyl "bag," also possibly Latin bucca "cheek").
bull (v.)youdaoicibaDictYouDict
"push through roughly," 1884, from bull (n.1). Related: Bulled; bulling.
bull (n.3)youdaoicibaDictYouDict
"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-dyke (n.)youdaoicibaDictYouDict
also bulldyke, 1926, from bull (n.1) + dyke.
bull-headed (adj.)youdaoicibaDictYouDict
also bullheaded, "obstinate," 1818, from bull (n.1) + head (n.).
bull-ring (n.)youdaoicibaDictYouDict
arena for bull fights, c. 1600, from bull (n.1) + ring (n.1).
bulla (n.)youdaoicibaDictYouDict
1876, from Latin bulla (plural bullae), literally "bubble" (see bull (n.2)).
bulldog (n.)youdaoicibaDictYouDict
c. 1500, from bull (n.1) + dog (n.). Perhaps from shape, perhaps because originally used for baiting bulls.
bulldoze (v.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
"person who intimidates by violence," 1876, agent noun from bulldoze (q.v.). Meaning extended to ground-clearing caterpillar tractor in 1930.
bullet (n.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
1560s, from bull (n.1) + finch; supposedly so called for the shape of its head and neck; compare French bouvreuil.
bullfrog (n.)youdaoicibaDictYouDict
also bull-frog, 1738, from bull (n.1) + frog (n.1). So called for its voice.
bullied (adj.)youdaoicibaDictYouDict
1851, past participle adjective from bully (v.).
bullion (n.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
1560s, from bull (n.1) + -ish; stock market sense is from 1882. Related: Bullishly; bullishness.
bullock (n.)youdaoicibaDictYouDict
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.)youdaoicibaDictYouDict
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.