[ad.di.tion] n [ME, fr. MF, fr. L addition-, additio, fr. addere] (14c) 1: a part added (as to a building or residential section)
2: the result of adding: increase
3: the act or process of adding; esp: the operation of combining numbers so as to obtain an equivalent simple quantity
4: direct chemical combination of substances into a single product -- in addition :
[2]besides, also -- in addition to : combined or associated with: [1]besides
2.