Also known as indifferent-sexual.
Means that a person is indifferent to having, primarily, a sexual relationship, but also is indifferent to a romantic or sensual relationship.
This is just the basis, though, and assumes you are bi-insexual, meaning you are indifferent to sex, but will take it from either gender.
Therefore, you can also be hetero-insexual, or homo-insexual, or pan-insexual.
Bob: "Dude, we might get laid tonight!"
Ron: "Ah, that's cool, but I don't really care, I'm insexual."