operation noun definition in Operations topic from the Oxford Advanced Learner's Dictionary

operation

 noun: Operations topic
(also British English, informal op) [countable] the process of cutting open a part of a person’s body in order to remove or repair a damaged part Will I need to have an operation? He underwent a three-hour heart operation. operation (on somebody/something) (to do something) an operation on her lung to remove a tumour operation (on somebody/something) (for something) Doctors performed an emergency operation for appendicitis last night.