cooperate [E17th] This comes from the Latin cooperari formed from co- ‘together’ and operari ‘to work’. The noun cooperation [LME] is considerably earlier. Cooperative [E17] developed the sense cooperative society in the early 20th century, although the abstract idea had been discussed for at least a century. The shortening co-op is much earlier than the full form, being found in 1871, which is probably an example of the luck that is needed to collect material for an accurate history of words.