a hypothetical sexuality beneath or worse than heterosexual, -NOT- gay, bisexual, pansexual, asexual or lesbian, usually used as an insult. could also be likened to ghey. can be used as a noun to describe a person fitting the description. usually used as an insult.
"he dude, he is SUCH a subhetero!"
"you guys are so subhetero, stealing my fucking couch"