1 [count] : a process in which a doctor cuts into someone's body in order to repair or remove a damaged or diseased part
▪ She is recovering from a major heart operation. [=she is recovering from major heart surgery] ▪ a minor/routine operation ▪ organ transplant operations 2 [count] a : a usually small business or organization
▪ The family runs a small farming operation. ▪ The company is a billion-dollar operation.
b : an activity of a business or organization — usually plural ▪ a company's banking operations ▪ An independent company has been hired to review the hospital's operations. 3 [noncount] : the state of functioning or being used — used with in or into ▪ The system is now in operation. ▪ The mill has been in operation for over 100 years. ▪ Safety goggles must be worn while the machine is in operation. [=in use] ▪ The dam will go into operation next month. 4 [noncount] : the way something functions or is used
▪ The camera's design allows for easy operation. ▪ the quiet operation of the printer 5 [count] : a set of planned actions for a particular purpose
▪ The city has launched an operation to clean up the neighborhood. ▪ Ten arrests were made in an undercover operation. ▪ a rescue operation ▪ The military operation gave them control of the city. ▪ peacekeeping operations 6 [count] : a single action performed by a computer
▪ The computer can perform millions of operations per second. 7 [noncount] : the act of using and controlling something
▪ He was arrested for unlicensed operation of a motor vehicle. 8 [count] mathematics : a mathematical process (such as addition or multiplication) that is used for getting one number or set of numbers from others according to a rule