co·op·er·ate 
(kō-ŏpə-rāt′)
(kō-ŏpə-rāt′)intr.v. co·op·er·at·ed, co·op·er·at·ing, co·op·er·ates
1. To work or act together toward a common end or purpose.
2. To acquiesce willingly; be compliant: asked the child to cooperate and go to bed.
3. To form an association for common, usually economic, benefit: When buyers cooperate, they can make large wholesale purchases at a discount.
[Late Latin cooperārī, cooperāt- : Latin co-, co- + operārī, to work (from opus, oper-, work; see op- in the Appendix of Indo-European roots).]
co·oper·a′tor n.