bigender vs gender-specific

bigender

adj
  • Having a tendency to move between feminine and masculine gender-typed behaviour depending on context. 

  • Having two genders simultaneously: both male and female. 

gender-specific

adj
  • Referring to a word or expression that refers to one gender only. 

How often have the words bigender and gender-specific occurred in a corpus of books? (source: Google Ngram Viewer )