A monosexual is someone who is sexually attracted to one sex (or gender) only, monosexuality being the corresponding sexual orientation. A monosexual could be, for example, heterosexual or homosexual.
^Then why even invent a…
I personally don’t see anything wrong with using one of these terms to define oneself if you think they work. It’s just shortform. It’s a lot easier to say “Pansexual” than it is “My sexual attraction is not dependant on a person’s gender or physical sex.” I understand that many people do not feel their sexuality should be given a word to define it when sexuality is a broad, ever changing spectrum, etc, and I respect that. I don’t assign labels to people who don’t want to be catagorized that way, but You can’t just tell people “Don’t use pansexual” “Don’t use Bisexual”, If I choose to use a word that encapsulates a complicated part of my indentity for the sake of convienience, who are you to not respect that choice?
Labels are not inherently evil, and there is no wrong way to express your sexuality as long as it is honestly and without cruelty or judgment.