The actual meaning of Mouthbreather is someone who has a deviated septum and therefore has trouble breathing through the nose. But people misunderstand the reason that they breathe through their mouths and misintepret it as an insult and don't realize that it is not their fault.
Poor John has a deviated septum and can't breathe very well through his nose. He doesn't have enough money or insurance for the surgery, so he has to endure all the insults and is labeled a mouthbreather
by Frostivers February 5, 2009
Golden State Warriors' Draymond Green
by Hughbabyyy May 7, 2018
anyone who you see with their mouth wide open, like a booger has clogged their nasal orifice. They just look like they're dumb, doing everything with their mouth open, with no care in the world.
by jeremy August 28, 2003
by Buxrmf January 22, 2021
Someone who breathed through their mouth instead of nose when they were younger, cussing their bones to mutate and making heir jaw and face look stupid and unattractive.
by Mayo Naze September 13, 2018
by bobbypoo May 24, 2005
Derogatory. Special species of fanboy dork who breathes through his mouth. When not collecting funny books, watching cartoons, playing dungeons and dragons, or video games, he is stalking goth girls or getting beat up.
The pimply faced mouthbreather with coke bottle glasses crept into the comic bookstore. He watched the goth girl for 5 minutes before he walked up and said to her, "Gee, (weez, weez, weez) you remind me of Electra from the X-Men funny books...(weez, weez, pant)
by Jerry Bathers January 21, 2006