coaction UK /kəʊˈakʃən/US /koʊˈækʃən/ noun3 •Collective or collaborative action. •The mapped version of an action to a cogroup.actions and coactions of measured groupoids on von Neumann algebras •(no longer used) Force; compulsion, either in restraining or impellingNovember 9, 1662, Robert South, Of the Creation of Man in the Image of God It had the passions in perfect subjection; and though its command over them was persuasive and political, yet it had the force of coaction, and despotical. formscoactions