noun

• The method by which a device performs its function.
• The method or practice by which actions are done.
• The act or process of operating; agency; the exertion of power, physical, mechanical, or moral.
• A planned undertaking.
• A business or organization.
• (medicine) A surgical procedure.
• (computing, logic, mathematics) A procedure for generating a value from one or more other values (the operands);
• (military) A military campaign (e.g. Operation Desert Storm)
• (obsolete) Effect produced; influence.