The only thing these crude, rude, and obnoxious people have in common with the human species is that they have a hole in their head with which they breath; otherwise, they are pretty much amoebas with vocal chords.

1. Someone who is incapable of breathing through their nose

2. Someone stupid who is unaware that their mouth is gaping open, often taking in gallons of air and spewing their own dry, bacteria rotten maw into your clean air in your vicinity.

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.

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.

Complete dumbass that finds it difficult to even breathe.

Someone incapable of breathing out their nose because their mouth is always yapping. They can often be seen in forums where they're assumed to be clever. However, assumptions usually land you in jail.

1. A term used by intolerant people or by the elite, who find some need, probably from a lack of self esteem, to marginalize someone whose opinion differs from their own. Usually they would define a mouth breather as someone who is to stupid to "get it". A a socially backward individual.

2. Someone who suffers from allergies or other condition that prevents breathing through the nose.