willfully (adv.)youdaoicibaDictYouDict[willfully 词源字典]
also wilfully, late Old English wilfullice "of one's own free will, voluntarily;" see willful + -ly (2). Mid-14c. as "deliberately, knowingly." Bad sense of "on purpose" is attested from late 14c.[willfully etymology, willfully origin, 英语词源]