variation (n.)youdaoicibaDictYouDict[variation 词源字典]
late 14c., "difference, divergence," from Old French variacion "variety, diversity" and directly from Latin variationem (nominative variatio) "a difference, variation, change," from past participle stem of variare "to change" (see vary). The musical sense is attested from 1801. Related: Variational.[variation etymology, variation origin, 英语词源]