permissive (adj.)youdaoicibaDictYouDict[permissive 词源字典]
c. 1600, "allowing to pass through," from Old French permissif, from Latin permiss-, past participle stem of permittere "to let go, let pass, let loose" (see permit (v.)). In sense of "tolerant, liberal" it is first recorded 1956; by 1966 it had definite overtones of sexual freedom. Earlier it meant "permitted, allowed" (early 15c.). Related: Permissively; permissiveness.[permissive etymology, permissive origin, 英语词源]