Noun

1. Financial transactions at a brokerage; having to do with the execution of trades and keeping customer records
2. The state of being in effect or being operative
3. A business especially one run on a large scale
4. A planned activity involving many people performing various actions
5. (computer science) data processing in which the result is completely specified by a rule (especially the processing that results from a single instruction)
6. Activity by a military or naval force (as a maneuver or campaign)
7. A medical procedure involving an incision with instruments; performed to repair damage or arrest disease in a living body
8. A process or series of acts especially of a practical or mechanical nature involved in a particular form of work
9. Process or manner of functioning or operating
10. (psychology) the performance of some composite cognitive activity; an operation that affects mental contents
11. (mathematics) calculation by mathematical methods
12. The activity of operating something (a machine or business etc.)