I understand where you're coming from.
As far as I'm concerned though: Bisexuality, in any form or subset, is the attraction to something other than the singular binary of attraction, which is Male or Female. Bisexuality and it's subsets cover attraction to both sexes, transgender, genderfluid, etc. Bisexuality (and you're somewhat correct is saying that the word refers to "two", in which case I would gladly change to saying Pansexual instead of Bisexual in this, as again, I see them as almost exactly the same thing) is just whatever attractions aren't within the Heterosexual/Homosexual singular binary. Bi (or Pan) is a multiple attraction. You experience attraction to both Females and Males. That can include cisgender, transgender, genderfluid, etc, as far as I understand because all of those are somewhere in the spectrum of Male to Female (both physically and internally).
Because everyone is unique. One "Bisexual" person can like males, transmales, transfemales, and genderfluid guys. Another can like females, transmales, transfemales, and males. Another can like genderfluid and transmales. Another can like transfemales and males. Etc. It's just no the singular male or female.
Heterosexuality is attraction to a female. Homosexuality is attraction to a male. And Bisexuality (or Pansexuality if you want that term to change) is attraction to everything in between.
And straight/gay people can be attracted to transgender/cisgender/etc as long as they follow the singular binary. Male or Female. So a straight female could like a male, transmale, genderfluid boy, etc. A gay female could like a female, transfemale, genderfluid female, etc. And so on.
If that made any sense.
Last edited: Sep 29, 2014