| 1. | used or engaged in performing operations: an operating surgeon. |
| 2. | of, for, or pertaining to operations: an operating budget. |
| 3. | of or pertaining to the proper operation of a machine, appliance, etc.: a manual of operating instructions. |
| 4. | Railroads. of, pertaining, or belonging to railroad workers, as engineers or firemen, who are directly engaged in the mechanical operation of trains: an operating union. |
verb, -at⋅ed, -at⋅ing.| 1. | to work, perform, or function, as a machine does: This engine does not operate properly. |
| 2. | to work or use a machine, apparatus, or the like. |
| 3. | to act effectively; produce an effect; exert force or influence (often fol. by on or upon): Their propaganda is beginning to operate on the minds of the people. |
| 4. | to perform some process of work or treatment. |
| 5. | Surgery. to perform a surgical procedure. |
| 6. | (of a drug) to produce the effect intended. |
| 7. | Military.
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| 8. | to carry on transactions in securities, or some commodity, esp. speculatively or on a large scale. |
| 9. | Informal. to use devious means for one's own gain; insinuate oneself; finagle: a man who knows how to operate with the ladies. |
| 10. | to manage or use (a machine, device, etc.): to operate a switchboard. |
| 11. | to put or keep (a factory, industrial system, ranch, etc.) working or in operation: to operate a coal mine. |
| 12. | to bring about, effect, or produce, as by action or the exertion of force or influence. |

operate op·er·ate (ŏp'ə-rāt')
v. op·er·at·ed, op·er·at·ing, op·er·ates
To perform surgery.