impose a penalty on; inflict punishment on; "The students were penalized for showing up late for class"; "we had to punish the dog for soiling the floor again"
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"
an accumulation of jobs not done or materials not processed that are yet to be dealt with (especially unfilled customer orders for products or services)