erratic (adj.)youdaoicibaDictYouDict[erratic 词源字典]
late 14c., "wandering, moving," from Old French erratique "wandering, vagrant" (13c.) and directly from Latin erraticus "wandering, straying, roving," from erratum "an error, mistake, fault," past participle of errare "to wander, err" (see err). Sense of "irregular, eccentric" is attested by 1841. The noun is from 1620s, of persons; 1849, of boulders. Related: Erratically.[erratic etymology, erratic origin, 英语词源]