I read a book in high school called ‘Bi America’ and it explained that there are probably certain levels of bisexuality. I don’t believe that because you are attracted, fantasize, or have kissed both sexes makes you bisexual. Because in my opinion bisexuality goes beyond that. I believe that people that call themselves bisexuals believe they could be in a relationship with either sex.
However, dictionary.com defines bisexuality as someone being sexually responsive to both sexes and being sexually attracted to both men and women.
So I guess its really up to who you are talking to. But as a bisexual, I believe it is someone that is not only attracted to and fantasizes about both sexes but can also someone that could be in a romantic/sexual relationship with either sex.