operation

noun

• 1 [mass noun] the action of functioning or the fact of being active or in effect:restrictions on the operation of market forces the company’s first hotel is now in operation
• [count noun] an active process; a discharge of a function:the operations of the mind

• 2an act of surgery performed on a patient: I’ve never felt better since my bypass operation

• 3 [often with adjective or noun modifier] an organized activity involving a number of people:a rescue operation
• a business organization; a company:he reopened his operation under a different name
• an activity in which a business is involved:the company is selling most of its commercial banking operations

• 4 Mathematics a process in which a number, quantity, expression, etc., is altered or manipulated according to set formal rules, such as those of addition, multiplication, and differentiation.