billyoudaoicibaDictYouDict[bill 词源字典]
bill: There are three distinct words bill in English (not counting the proper name), and of them all, the most recent is the commonest. Bill ‘note of charges’ [14] comes from Anglo-Latin billa, which is probably a variant of Latin bulla ‘_document, seal’ (as in ‘papal bull’). English billet [15], as in ‘billeting soldiers on a house’, was originally a diminutive form of billa (French billet ‘letter’ comes from the same source). Bill ‘hook-bladed weapon’ [OE], now found mainly in billhook, comes from a prehistoric West Germanic *bilja, which may be based ultimately on Indo-European *bhid-, source of English bite. Bill ‘beak’ [OE] may be related to bill ‘weapon’, but this is not clear.

The verbal sense ‘caress’, as in ‘bill and coo’, is 16th-century; it arose from the courting behaviour of doves stroking each other’s beaks.
=> billet[bill etymology, bill origin, 英语词源]
bill (n.1)youdaoicibaDictYouDict
"written statement," mid-14c., from Anglo-French bille, Anglo-Latin billa "list," from Medieval Latin bulla "decree, seal, sealed document," in classical Latin "bubble, boss, stud, amulet for the neck" (hence "seal;" see bull (n.2)). Sense of "account, invoice" first recorded c. 1400; that of "order to pay" (technically bill of exchange) is from 1570s; that of "paper money" is from 1660s. Meaning "draft of an act of Parliament" is from 1510s.
bill (n.2)youdaoicibaDictYouDict
"bird's beak," Old English bill "bill, bird's beak," related to bill, a poetic word for a kind of sword (especially one with a hooked blade), from a common Germanic word for cutting or chopping weapons (compare Old High German bihal, Old Norse bilda "hatchet," Old Saxon bil "sword"), from PIE root *bheie- "to cut, to strike" (cognates: Armenian bir "cudgel," Greek phitos "block of wood," Old Church Slavonic biti "to strike," Old Irish biail "ax"). Used also in Middle English of beak-like projections of land (such as Portland Bill).
bill (v.)youdaoicibaDictYouDict
"to send someone a bill of charge," 1864, from bill (n.1). Related: Billed; billing.
bill (n.3)youdaoicibaDictYouDict
ancient weapon, Old English bill "sword (especially one with a hooked blade), chopping tool," common Germanic (compare Old Saxon bil "sword," Middle Dutch bile, Dutch bijl, Old High German bihal, German Beil, Old Norse bilda "hatchet." See bill (n.2).