passable (adj.)youdaoicibaDictYouDict[passable 词源字典]
early 15c., "that may be crossed," from pass (v.) + -able, or from Old French passable "fordable, affording passage" (14c.). Sense of "tolerable" is first attested late 15c. Related: Passably.[passable etymology, passable origin, 英语词源]