ŏp'er-ā'tion, n.

n. [Lat. operatio, Fr. opération, Pr. operacio, Sp. operacion, It. operazione.] 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.

2. The method of working; mode of action. “Many medicinal drugs of rare operation.” Heylin.
3. That which is operated or accomplished; an effect brought about by a definite plan; as, military or naval operations.
4. Effect produced; influence.

The bards were next the druids in regard, and played excellently to their songs on their harps, whereby they had great operation on the vulgar. Fuller.

5. (Math.) Something to be done; some transformation to be made upon quantities, which transformation is indicated either by rules or symbols.
6. (Surg.) Any methodical action of the hand, or of the hand with instruments, on the human body, with a view to heal a part diseased, fractured, or dislocated, as in amputation, and the like.