immutable (adj.)youdaoicibaDictYouDict[immutable 词源字典]
early 15c., from Old French immutable and directly from Latin immutabilis "unchangeable," from assimilated form of in- "not, opposite of" (see in- (1)) + mutabilis "changeable," from mutare "to change" (see mutable). Related: Immutably.[immutable etymology, immutable origin, 英语词源]