surgery
used as an uncountable noun
In both British and American English, surgery is medical treatment in which a person's body is cut open so that a surgeon can deal with a diseased or damaged part.
He underwent surgery to repair a torn knee ligament.
She may have to have more surgery on her wrist.
used as a countable noun
A surgery can be used to refer to a particular medical operation. This meaning is used more in American English than British English.
He has had five knee surgeries.
She was told she would have to have another surgery.
In British English, a doctor's or dentist's surgery is the building or room where he or she works and where people go to receive advice and minor treatment.
I called the surgery to make an appointment.
In American English, a building or room like this is called the doctor's or dentist's office.
Dr Patel's office was just across the street.