Definition of genderist:
(adj) :
Pertaining to or exhibiting genderism, a belief that gender is rigid, binary, and determined by sex.
(n) :
(uncommon, in right-wing usage, derogatory) One who believes in gender ideology or does not support traditional gender roles.
(n) :
(rare) One who discriminates based on gender.
(n) :
(rare) One who studies gender.