hospital vs operating theatre

hospital

noun
  • A large medical facility, usually in a building with multiple floors, where seriously ill or injured patients are given extensive medical and/or surgical treatment. 

  • A building founded for the long-term care of its residents, such as an almshouse. The residents may have no physical ailments, but simply need financial support. 

operating theatre

noun
  • A room in a hospital used for performing surgery (originally designed for operations in front of observers). 

How often have the words hospital and operating theatre occurred in a corpus of books? (source: Google Ngram Viewer )