The concept that no form of social oppression are exclusive from each other, and are rather intimately interconnected.
- sexism is not exclusive from racism
- homophobia is not exclusive from sexism
- and such
An important concept to consider is the idealization of Eurocentric, heterosexual, masculine ideal as a specific default; anything outside of that category would be socially oppressed in some form or another, moreso the less it fits into said ideal.