Co-oping, which means working together or collaborating, has a number of antonyms depending on the context. For instance, if one thinks of co-oping in terms of supporting a shared goal or effort, then going against or undermining that effort might be considered an antonym. In this sense, words like hindering, impeding, and obstructing could be used to describe the opposite of cooperating. Similarly, if one thinks of co-oping as building rapport or a positive relationship with others, then being antagonistic or competitive might be considered an antonym. Words like clashing, opposing, and struggling could be used to describe the opposite of cooperation in this context.