mouth-breather(redirected from a mouthbreather)
A dimwitted, foolish, or idiotic person; someone of low or stunted intelligence. Used as an insult. I'm tired of getting picked on by these mouth-breathers. I can't wait to go to college where I can meet people who aren't afraid to think.
n. a stupid-acting person. I always end up with a mouth-breather on a blind date.