coy (adj.)

early 14c., "quiet, modest, demure," from Old French coi, earlier quei "quiet, still, placid, gentle," ultimately from Latin quietus "free; calm, resting" (from PIE root *kweie- "to rest, be quiet"). Meaning "shy" emerged late 14c. Meaning "unwilling to commit" is 1961. Related: Coyly; coyness.