girlfriend vs niece

girlfriend

noun
  • A female friend. 

  • A female partner in an unmarried romantic relationship. 

  • A fellow gay man, especially a friend as opposed to a sexual partner. 

  • A term of address for a female friend or among gay men. 

niece

noun
  • A daughter of one’s cousin or cousin-in-law 

  • A daughter of one’s sibling, brother-in-law, or sister-in-law; either the daughter of one's brother ("fraternal niece"), or of one's sister ("sororal niece"). 

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