"exercise book; report of proceedings," c. 1845, "book of loose sheets tacked together," from French cahier "writing book, copy-book," originally a bookbinding term, from Old French cayer, originally quaier "sheet of paper folded in four," from Vulgar Latin *quaternus, from Latin quaterni "four each," from quater "four times" (from PIE root *kwetwer- "four"). Compare quire (n.1).