1. To perform a function; to work: The motor operates smoothly.
2. To perform surgery.
3. To exert an influence; such as, forces operating on the economy.
4. To produce a desired or proper effect;for example, a drug that operates quickly.
5. To carry on a military or naval action or campaign.
6. To conduct business in an irregular or devious manner; such as, drug dealers operating in residential and school areas.

Disk Operating Ssystem operating system.

The voltage, applied across the electrodes in the detecting chamber of a radiation detection instrument, that enables the detection of an ionizing event.