Someone who doesn't experience sexual attraction. Often confused with autosexual (sexually attracted to oneself), asexual reproduction (when organisms can reproduce without sex), celibacy/abstinence (the choice not to have sex). Asexuals may or may not be romantically attracted to others, and may or may not have a sex drive (though not directed towards anyone or anything).
Asexuality is _not_ a choice, and you cannot decide to become one. They are just born that way, the same way as people are straight, gay, bi, or whatever.
1. Jill: I hate men, I'm just going to become asexual
Me: no, you can't "become" asexual
2. I am asexual, I am not attracted to men or women.