1. The act or process of operating; agency; the exertion of power, physical, mechanical, or moral. The pain and sickness caused by manna are the effects of its operation on the stomach. (locke) Speculative painting, without the assistance of manual operation, can never attain to perfection. (Dryden)
6. (Science: surgery) Any methodical action of the hand, or of the hand with instruments, on the human body, to produce a curative or remedial effect, as in amputation, etc. Calculus of operations. See Calculus.
Origin: L. Operatio: cf. F. Operation.