quire (n.1)

c. 1200, "set of four folded pages for a book; pamphlet consisting of a single quire," from Anglo-French quier, Old French 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"). Meaning "standard unit for selling paper" first recorded late 14c. In quires (late 15c.) means "unbound."

early form and later variant spelling of choir (q.v.).