"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.
"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 (cf. Old High German bihal, Old Norse bilda "hatchet," Old Saxon bil "sword"), from PIE root *bheie- "to cut, to strike" (cf. 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 (e.g. Portland Bill).
ancient weapon, Old English bill "sword (especially one with a hooked blade), chopping tool," common Germanic (cf. Old Saxon bil "sword," Middle Dutch bile, Dutch bijl, Old High German bihal, German Beil, Old Norse bilda "hatchet." See bill (n.2).