Quits

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late 15th century (in the sense ‘freed from a liability or debt’): perhaps a colloquial abbreviation of medieval Latin quittus, from Latin quietus, used as a receipt (see quietus).

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quits

quits

etymonline

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quits (adj.)

"on even terms with one another," in to be quits (with one) "have made a mutual satisfaction of claims or demands," 1660s; earlier "discharged of a liability" (c. 1200), perhaps from Medieval Latin quittus (see quit (adj.)). An adjective used as a quasi-noun in plural form. Quit (adj.) "satisfied" is attested from c. 1400.