1 [mass noun] the action of functioning or the fact of being active or in effect:restrictions on the operation of market forcesthe 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.