bigender vs genderfluid

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. 

genderfluid

adj
  • Not having a fixed gender; having a gender which changes from time to time. 

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