n. 1. An impelling or restraining force; a compulsion. 2. Joint action. 3. Ecology Any of the reciprocal actions or effects, such as symbiosis, that can occur in a community. [Middle English coaccioun, from Latin coāctiō, coāctiōn-, a collecting, from coāctus, past participle of cōgere, to collect, condense; see COAGULUM. Senses 2 and 3 : CO- + ACTION.] co·active adj. co·active·ly adv. |
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