To Cooperate

1. (intransitive) To work or act together, especially for a common purpose or benefit.
2. (intransitive) To allow for mutual unobstructed action
3. (intransitive) To function in harmony, side by side
4. (intransitive) To engage in economic cooperation.

Usage note

• The usual pronunciation of 'oo' is /uː/ or /ʊ/. The dieresis in the spelling coöperate – now obsolete outside the pages of The New Yorker – was intended to emphasize that the second o begins a separate syllable.
• The solid form is much more common than the hyphenated form in both British and American corpora. The hyphenated form used to be more common in British usage, but is no more.^[1]

Synonyms

• coact
• coadjute
• co-op
• make common cause