bullyoudaoicibaDictYouDict[bull 词源字典]
bull: There are three distinct words bull in English. The oldest is the animal name, which first appears in late Old English as bula. Related forms occur in other Germanic languages, including German bulle and Dutch bul. The diminutive bullock is also recorded in late Old English. The second bull is ‘edict’ [13], as in ‘papal bull’. This comes from medieval Latin bulla ‘sealed document’, a development of an earlier sense ‘seal’, which can be traced back to classical Latin bulla ‘bubble’ (source also of English bowl, as in the game of bowls; of boil ‘heat liquid’; of budge [16], via Old French bouger and Vulgar Latin *bullicāre ‘bubble up, boil’; and probably of bill ‘statement of charges’).

And finally there is ‘ludicrous or selfcontradictory statement’ [17], usually now in the phrase Irish bull, whose origins are mysterious; there may be a connection with the Middle English noun bul ‘falsehood’ and the 15th-to 17th-century verb bull ‘mock, cheat’, which has been linked with Old French boler or bouller ‘deceive’. The source of the modern colloquial senses ‘nonsense’ and ‘excessive discipline’ is not clear.

Both are early 20th-century, and closely associated with the synonymous and contemporary bullshit, suggesting a conscious link with bull the animal. In meaning, however, the first at least is closer to bull ‘ludicrous statement’. Bull’s-eye ‘centre of a target’ and ‘large sweet’ are both early 19th-century. Bulldoze is from 1870s America, and was apparently originally applied to the punishment of recalcitrant black slaves; it has been conjectured that the underlying connotation was of ‘giving someone a dose fit for a bull’.

The term bulldozer was applied to the vehicle in the 1930s.
=> phallic; bill, bowl, budge[bull etymology, bull origin, 英语词源]
bull (n.1)youdaoicibaDictYouDict
"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 (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.