registered nurse vs sitter

registered nurse

noun
  • A professional nurse who is a licensed graduate of a university or college of nursing who has successfully passed an examination such as NCLEX-RN. 

sitter

noun
  • A very easy scoring chance. 

  • One employed to watch or tend something; a babysitter, housesitter, petsitter, etc. 

  • A broody hen. 

  • A participant in a séance. 

  • Someone who sits, e.g. for a portrait. 

How often have the words registered nurse and sitter occurred in a corpus of books? (source: Google Ngram Viewer )