1. Someone who is really dumb
2. A person who doesn't/can't breathe through their nose

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

1. literally, someone who lacks enough intelligence that they never learned to breathe through their nose.

2. a really dumb person.

General term for a fucking idiot.

Usually seen with a blank stare on their face, mouth slightly agape, and possibly a little bit of drool coming out.

A stupid person who breathes through their mouth, like P Diddy.

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.

A person who breathes through their mouth, thus having their mouth hang open. Their mouth can be anywhere from barely open, to gaping, and usually the more open it is, the more idiotic, and unintelligent they look. Mouth Breathers may or may not be intelligent, however, due to the fact that they don't realize their mouth is gaping, they just look like a moron, who may drool at any moment, but is deffinately sucking in as much air as possible.

Mouth breathers tend to be people who are bored, zoning out, very focused on something, someone with huge lips, or someone who isn't smart enough to realize their mouth is hanging open, catching flys. All tend to appear as the latter.

People who are sick and can't actually breathe through their noses do not count.