The following terminology explains the way I perceive the world at the time of this writing. It should help in understanding the rest of the text:
Sex: whether a mammal is female or male in terms of reproductive function.
Female, male: See sex.
Patriarchy: a large and varied set of social institutions (cultural, legal, economic, …) that altogether serve to provide power and privilege to male people, while exploiting female people.
Sexism/misogyny: a set of patriarchal belief systems –and the act of proliferating these– which serve to convince people that males are physically and metaphysically superior to females, thus justifying patriarchy.
Gender: the socially constructed identities of boyhood/manhood, and girlhood/womanhood, in terms of expected personality traits, mannerisms, attire, and so on. A big part of sexism. (I might say “the male/female gender” so as not to constantly have to use both the child and adult variants of the words; this is merely an abbreviation and not meant to conflate sex and gender.)
Masculine/masculinity, feminine/femininity: that which is perceived as being proper for the male and female genders, respectively. I.e. the concrete characteristics associated with each identity, isolated from the identity itself. (To say “the girl is a boy” is a contradiction since these are exclusive categories, but one can say “the girl is masculine” to speak of a deviancy, in terms of gender.)
Girl/woman, boy/man: A child/adult female, and child/adult male, respectively, who by virtue of their sex are expected to conform to the corresponding gender; otherwise their existence is a threat to patriarchy.
Gender abolitionism: the idea that the concept of gender should be rendered irrelevant in society, and that girls, women, boys, and men should therefore not be expected to have certain personality traits, attire, etc. anymore, thus undermining one of the biggest pillars of patriarchy. (One could say this means it becomes acceptable for a man to be feminine and vice versa, although the concepts of “feminine” and “masculine” would fade into obscurity over time anyway, just like, say, “miscegenation”.)