Antonyms for "was joined with" could include separation, detachment, isolation, division, disconnection, and segregation. When two things are joined or connected, these antonyms represent the opposite, indicating that the two things are apart or separate. These words could be used to describe physical objects, people, concepts or ideas that were previously linked but are now separate or distant. For example, instead of saying "the two groups were joined together for the project," one could say "the two groups were segregated for the project." In summary, antonyms for "was joined with" describe the opposite of connection or unity.