Most people do agree that sexism is the discrimination or hatred of a sex. Some people, though, label things that are not sexist as sexist.
Women can be sexist too
A very small amount of people argue that women cannot be sexist, because men have the power. This is completely false. Sexism is the discrimination of someone because of their sex. Thus, if a woman discriminates against a man, it is sexist. Same thing if the roles were reversed.
Commonly confused discrimination that is labeled sexist
A lot of people say discriminating against someone because they are a different "gender" than regular people, is sexism. I will not be going over if I believe in this "gender" thing or not, all I am saying is if this concept of "gender" is true, discriminating against someone of another "gender" because they do not belong in the two genders is not sexism. This is due to the fact, if this "gender" idea is actually true, you would be discriminating against them because of "gender" not because of their sex.
Affirmative Action and Sexism
Some people think that doing something sexist to help a group that sometimes gets discriminated against is not sexist. This is not true. Affirmative action seeks to "level the playing field", but in all reality it is a form of sexism. It is sexist because it will place another sex, typically females, ahead of males just because they are females.
Sexism verse Insults
Some people think insulting someone of the opposite sex's looks is sexist. This is not true. For example, telling someone that they look ugly because they have small breasts is not sexism. Saying someone is a "stupid man/woman" is not sexism either, because you are not saying they are stupid because they are a man/woman. Now if you say something like, "you are stupid like every other man/woman", that is sexism, because you are calling everyone that is a man/woman stupid.
Movements and Sexism
Not supporting a movement does not make you a sexist. Some people claim that if you are not a feminist, you are sexist. This is not true. I do not support feminism because I hate women. I do not support feminism because to me feminism is not about equal rights. I do agree with equal rights for the sexes, but I do not believe that feminism stands for equal rights. Since I do believe men and women are equal and should have the same rights, I am not a sexist; even though I do not agree with feminism.