- -ion -ion (?; 106). [L. -io, acc. -ionem: cf. F. -ion.] A noun suffix denoting act, process, result of an act or a process, thing acted upon, state, or condition; as, revolution, the act or process of revolving; construction, the act or process of constructing; a thing constructed; dominion, territory ruled over; subjection, state of being subject; dejection; abstraction. [1913 Webster]
The Collaborative International Dictionary of English. 2000.