Co-op is short for the noun cooperative, which refers to a jointly owned or operated enterprise or organization. It has no other meanings. If you’re looking for a verb meaning to take for one’s own use, the word you want is co-opt. That t is crucial.
Inflected, co-opt makes co-opting and co-opted. Co-op is never inflected because it is a noun (although it can function as an adjective). Both words are usually hyphenated to reflect pronunciation (and to prevent confusion with coop).
Examples
Oswego’s gymnastics program is a co-op team that includes gymnasts from both Oswego and Oswego East high schools. [Beacon News]
This is why so many mainstream progressive groups will try to co-opt the OWS movement, much like the original Tea Party was co-opted by the mainstream conservative movement. [The Atlantic]
Members of the Northern Alliance Housing Co-Op intend to buy properties by raising capital from lenders. [Liverpool Echo]
Rather than trying to co-opt a faction, government agencies will do well to allow the diversity of voices to be heard. [Sydney Morning Herald]
Morton is calling on his fellow biodiesel enthusiasts to come together as a co-op group. [Vancouver Sun (article now offline)]
The problems began with the decision 10 years ago to co-opt the hated warlords as our agents for overturning the Taliban regime. [Telegraph]