I. kōˈakshən noun
( -s )
Etymology: Middle English coaccioun, from Middle French coaction, from Latin coaction-, coactio collection, from coactus (past participle of cogere to collect, compel) + -ion-, -io -ion — more at cogent
: force or compulsion in restraining or impelling : control
II. (ˈ)kō+ noun
Etymology: co- + action
1. : action taken together : joint action : an acting together
2. : the relation or interaction that exists between individuals or kinds of organisms (as species) in an ecological community and typically takes the form of cooperation, disoperation, or competition — compare reaction