Any human being that breathes in and out through their mouths, often engaging in idiotic and useless activity. An affinity for sexually crude humour generally accompanies.
by Mhuur November 25, 2002

Mouth breather was used by Jennifer Love Hewitt in Heartbreakers. She was annoyed with a guy who she considered a stupid idiot. It was later used sever times in Stranger Things.
by TInaJack February 26, 2018

1. A moron from a low social caste. Picture someone with a sunken forehead, low hairline, and prominent chin.
2. A guy who goes to the gym seven days a week, probably does steroids, and has a body that looks like a comic-book character. He might be 5'4" but his arms and shoulders are so overbuilt that he looks ridiculous.
2. A guy who goes to the gym seven days a week, probably does steroids, and has a body that looks like a comic-book character. He might be 5'4" but his arms and shoulders are so overbuilt that he looks ridiculous.
by phuckie July 14, 2007

A sun smilin' mouth-breather.
One who can't look towards the sun without squinting, showing their upper teeth and dropping their mouth open.
Usually wears a Cleveland Browns shirt.
One who can't look towards the sun without squinting, showing their upper teeth and dropping their mouth open.
Usually wears a Cleveland Browns shirt.
"Hey look at that sun smilin' mouth breather, I sure hope a cloud blocks out that sun before he drools all over himself."
by F.R. January 07, 2005

by fartknocker4 August 11, 2003

Someone who's been in too many fistfights and thus has had the ability to breathe through the nose beaten out of him. The usual implication is that the ability to use the brain has also been beaten out of him.
My bookie sent a mouth breather to collect for him, but when the goon tried to get me to head to the ATM with him I escaped for the moment by saying his shoe was untied.
by Rockford Files May 13, 2005

A Conservative.
by The Polish Parrothead August 12, 2009
