1. (a.) Cooperating.

2. (n.) An adjuvant.

aid aide aide-de-camp coacting coactive coadjutor coadjuvant coefficient collaborative collective collectivist collectivistic collusive combine combined commensal common communal communalist communalistic communist communistic communitarian concerted concordant concur concurrent concurring conjoin conniving cooperant cooperate cooperating cooperative ecumenic fellow harmonious harmonized joint league lieutenant mutual noncompetitive reciprocal symbiotic synergetic synergic synergistic uncompetitive