faithfullyEnglishOxford New American Dictionaryfaithfully /ˈfāTHfəlē, ˈfeɪθfəli / ▸ adverb 1 in a loyal manner: he swore that he would serve the king faithfully. 2 in a manner that is true to the facts or the original: she translated the novel as faithfully as possible. – PHRASES yours faithfully British a formula for ending a formal letter to someone whose name you do not know.