late 15c., from Middle French délinquant, from present participle of délinquer (15c.), and directly from Latin delinquentum (nominative delinquens), present participle of delinquere "to fail; be wanting, fall short; offend," from de- "completely" (see de-) + linquere "to leave" (see relinquish). As an adjective, from c.1600.