Co-action is a word that refers to the phenomenon of working together to achieve a common goal. Antonyms for co-action can be anything that goes against the philosophy of collaboration and teamwork. Some of the potential antonyms for co-action could be individualism, selfishness, complacency, competition, and apathy. These words all describe actions or mindsets that negate the concept of working towards a common goal. In a world that is increasingly interconnected and complex, co-action is becoming more and more important. Anything that detracts from it is something that should be avoided or overcome if progress is to be made.