From Middle English, borrowed from Old French, from Latin quietus, past participle of quiescere (“to keep quiet, rest”). Doublet of coy and quietus.
First attested 1490. From Latin quietus, in this form probably a borrowing or a semi-learned term; cf. also the Old Catalan form quet, queda, which was likely inherited.
Borrowed from Latin quiētus, from quiēs (“rest”). Doublet of coi, which was inherited, and quitte, another borrowing.
From Latin quietus.