Learn English – the antonym of likewise

Etymologically "Feminism" is derived from "female" and historically it has referred to women's rights. But the term — as a sociological term as well as a social movement — has evolved in many ways, so while for some "feminism" is the struggle for women's rights in society, others will explain that feminism is the struggle to remove gender-biases from society, and as such applies to men's rights as well as women's.

So when you're looking for the complementary term to feminism, you need to know exactly which meaning of feminism you're going for, because in many contexts "feminism" might be enough for you.

Also, it should be noted that even if we find a term that says "mens' rights" to complement feminism as womens' rights, they will never be entirely parallel in tone and connotation, because mens' rights and women's rights aren't symmetrical. If (some versions of) feminism describes itself as the struggle to achieve equal rights in a male-dominated world, a totally equivalent term would have to imply a similar male struggle, which is, well, a bit of a stretch.

Typical scientific/technical jargon in this kind of sentence is this:

occurrence/nonoccurrence

and

presence/absence