Meaning of OPERATION in English

■ noun

1》 the action or process of operating.

2》 an act of surgery performed on a patient.

3》 an organized activity involving a number of people: a rescue ~.

4》 a business organization; a company.

5》 Mathematics a process in which a number, quantity, expression, etc. is altered or manipulated according to set formal rules.

Concise Oxford English vocab.      Сжатый оксфордский словарь английского языка.