addition (n.)

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 "add to, join, attach" (see add). Phrase in addition to "also" is from 1680s.