Ahh
that you didn't know what
bisexual had meant
I could still fall under "bi-curious" where I honestly don't know related to the fact of not having had "sex" with a woman before
I think the term "bisexual" could be vast related to people that are into both men or women
opposite or same sex
So having had kissed both genders
having had full make out sessions with women has me seeing myself as a "bisexual"
For your friend
maybe falls under "trangender" related to how I know of stories of people that make the transformation of changing gender
Other people could be right that it may not just be that one person where your friend could be "bisexual"
Only we know ourselves what we are
your friend could be right that its just that ONE person because for me as a bisexual, I am into both men and women
right from the get go I find women hot and have had experiences with women
So your friend could very well be just into that one person but not into any other same sex