With that said, here's the top paragraph from Wikipedia; reading it, I totally concur with this definition so I think we can start from here:
"Gender is the range of characteristics pertaining to, and differentiating between, masculinity and femininity. Depending on the context, these characteristics may include biological sex (i.e. the state of being male, female or an intersex variation which may complicate sex assignment),
Okay, I'm generally fine with that definition, a usable definition of "masculinity" and "femininity" is required. Although I would point out that as is common in more controversial Wikipedia topics, this first definition can easily contradict the second, and lead to opposite results. In other words, Wikipedia is not giving a single, clear definition. Rather, it is simply listing
different definitions for the word "gender".
Bingo!! That is exactly my point, and that's the one that should be discussed to see if it is a sufficient justification to change the meaning of male/female/man/woman/boy girl
or gender identity.[1][2][3] Some cultures have specific gender roles that can be considered distinct from male and female, such as the hijra (chhaka) of India and Pakistan."
Using the word to define the word is bogus, and we're not in India or Pakistan anyway. So we're left with what is behind door No. 2.
I'm going to add something here to see if I can convey my point more clearly. You have previously noted that "male" and "female" are binary/polar terms. You
also have stated that you have misgivings about whether "gender" is, in fact, binary or polar, and that it may actually be more of a continuum. And in terms of how "gender" has been defined even in your Wikipedia example (the second and even third referring to
roles in society), I'd tend to agree. "Gender" is not binary/polar at all. It is a continuum.
It seem not only misleading, but irrational, to redefine binary terms and use them to describe something that is
not binary. In contrast, given that the vast majority of the population does fall within the binary biological/reproductive sexual division, it would make sense to continue using those binary terms to describe characteristics that are, in fact, binary.