Noun
(usually uncountable) A belief that gender is rigid, usually a belief that it is binary, comprising male and female, and that the aspects of a person's gender are inherently linked to their sex at birth.
Belief that one gender is superior; discrimination on the basis of gender. (Compare sexism.)
(in right-wing usage, derogatory) Opposition to traditional gender roles; belief that gender exists separate from sex; "gender ideology"; a variously-defined catch-all for things like transgender rights and feminism to which antigenderism is opposed.
(countable) A gendered or gender-stereotyped behaviour, activity or statement.
Source: en.wiktionary.org