Why is the ninth month called September?
"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).
To kiss and cuddle like lovebirds: bill and coo in the corner