why are operating room nurses called theatre nurses?

Answer 1

In teaching hospitals many operating rooms are set up more or less as theaters, with areas where interns and students can observe a procedure.

Many of these hospitals refer to all operating rooms as theaters and therefore an O.R. nurse would be known as a theater nurse. I believe the terminology is more common in Britain than it is in the U.S.

Answer 2

Because the operations/operating room can also be called an operating theatre.

Answer 3

Surgical rooms are called operation theatres.

Answer 4

Because of hospitals that have operating rooms with observation rooms or theatres.