The phrase "was cahoots with" carries the connotation of collaboration, partnership, or collusion. Its antonyms would include words and phrases that signify the opposite of these meanings, such as antagonistic, uncooperative, unconnected, unrelated, and independent. Other antonyms could include disavowal, denouncement, condemnation, opposition, and disapproval. When someone is not "in cahoots with" another person or organization, they are typically operating on their own, with their own interests, goals, and motives. Using antonyms for "was cahoots with" can convey a strong sense of separation, distrust, and opposition between the parties involved.