addition (n.)youdaoicibaDictYouDict[addition 词源字典]
late 14c., "action of adding numbers;" c. 1400, "that which is added," from Old French adition "increase, augmentation" (13c.), from Latin additionem (nominative additio) "an adding to, addition," noun of action from past participle stem of addere (see add). Phrase in addition to "also" is from 1680s.[addition etymology, addition origin, 英语词源]