from The American Heritage® Dictionary of the English Language, 4th Edition
- intransitive v. To work or act together toward a common end or purpose.
- intransitive v. To acquiesce willingly; be compliant: asked the child to cooperate and go to bed.
- intransitive v. To form an association for common, usually economic, benefit: When buyers cooperate, they can make large wholesale purchases at a discount.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To work or act together, especially for a common purpose or benefit.
- v. To allow for mutual unobstructed action
- v. To function in harmony, side by side
- v. To engage in economic cooperation.
Late Latin cooperārī, cooperāt- : Latin co-, co- + operārī, to work (from opus, oper-, work; see op- in Indo-European roots).(American Heritage® Dictionary of the English Language, Fourth Edition)
Originated 1595–1605 from Late Latin cooperatus ("work with"). See co- + operate. (Wiktionary)