acceptable (adj.)youdaoicibaDictYouDict[acceptable 词源字典]
late 14c., from Old French acceptable, from Latin acceptabilis "worthy of acceptance," from acceptare "take or receive willingly" (see accept). Related: Acceptably.[acceptable etymology, acceptable origin, 英语词源]
unacceptable (adj.)youdaoicibaDictYouDict
late 15c., from un- (1) "not" + acceptable. Related: Unacceptably.