tomgirl vs weak sister

tomgirl

noun
  • Synonym of tomboy (“girl who behaves in a typically boyish manner”) 

  • A boy who behaves in a typically girlish manner. 

weak sister

noun
  • A person who is cowardly or indecisive. 

  • A person or thing which is the least robust or least dependable member of a group. 

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