/əˈdɪʃn ||; əˈdɪʃən/noun1 [U] adding sth, especially two or more numbers 加，相加（尤指把两个或以上的数目相加） ☞Look at subtraction. 参看 subtraction。
2 [C] an addition (to sth) a person or thing that is added to sth 增加的人或物
in addition (to sth) as well as 除了…外:
She speaks five foreign languages in addition to English. 除了英语外，她还会说五种外语。