A movement created to promote equal rights of men and women alike, simply put.
Many definitions try to degrade this notion by stating that it has backfired and turned into a reason for hating men. This is not the case. The reason people would think this is because in today's society many men are still raised on the notion that women are inferior and must be oppressed. They therefore promote hate against equal rights between men and women and try to degrade it in any way possible. Note that not all men are like this, but the majority are.
There will always be sexist men. That is the unfortunate truth.
Feminism is a notion to equalize the fields and make people realize that men and women are equal in every way.
Feminism does NOT support hate against men, it merely states that men are NOT SUPERIOR TO WOMEN. Get it in your goddamn heads, people.