Similar word to co-active:
agreeing, coacting, coactive, coadjuvant, coefficient, collaborating, collaborative, collective, collegial, collusive, combined, combining, common, concerted, concurring, coordinated, hand in glove, harmonious, in league, interdependent, joining, participating, reciprocal, shared, symbiotic, synergetic, synergic, team, united, uniting
agreeing, coacting, coactive, coadjuvant, coefficient, collaborating, collaborative, collective, collegial, collusive, combined, combining, common, concerted, concurring, coordinated, hand in glove, harmonious, in league, interdependent, joining, participating, reciprocal, shared, symbiotic, synergetic, synergic, team, united, uniting