According to Wikipedia,
“Feminism is a range of movements and ideologies that share a common goal: to define, establish, and achieve equal political, economic, cultural, personal, and social rights for women.
This includes seeking to establish equal opportunities for women in education and employment. A feminist advocates or supports the rights and equality of women.”
You can be a frum feminist, just as you can be a frum
environmentalist*, but the thing is that when feminism
and the Torah or contemporary chareidi/Orthodox practice
conflict, those who are frum and feminists often think
that it is not feminism but Judaism which should yield,
which is obviously not acceptable.
*I don’t know how appropriate “isms” that aren’t Judaism are for a Jew.