make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of; "We added two students to that dorm room"; "She added a personal note to her letter"; "Add insult to injury"; "Add some extra plates to the dinner table"
make an addition by combining numbers; "Add 27 and 49, please!"
state or say further; "`It doesn't matter,' he supplied"
constitute an addition; "This paper will add to her reputation"
work together on a common enterprise of project; "The soprano and the pianist did not get together very well"; "We joined forces with another research group"
cooperate as a traitor; "he collaborated with the Nazis when they occupied Paris"