1 and, added to, increased by, with the addition of, with an increment of, (coupled) with, together with:
Two plus three equals five. Your initial deposit plus accumulated interest will make a substantial sum.
2 added, additional, supplementary, extra:
One must take into account the plus value of the good publicity.
3 addition, bonus, extra, gain, benefit, asset, advantage, profit, return:
Improvements constitute a big plus in evaluating the building.