sexism

Short definition from Wiktionary

Noun

1. 1
   The belief that people of one sex (or gender) are inherently different from those of another sex, and generally that one sex is superior to others.
2. 2
   Discrimination or different treatment based on sex or gender, especially discrimination against women.
3. 3
   Attitudes or actions that are based on or promote the expectation that people adhere to stereotypical social roles (gender roles) based on sex.