One who doesn't know how to breathe through their damn nose, causing them to constantly pant like dogs.
"Dude, Steve is such a fucking mouth breather"
A person who without hesitation wil tell on you or someone who gossips too much and wont keep their mouth shut
You know the feds will be at your door if bob knows what you're doing, he's a mouth breather.
Someone who no longer wears a mask indoors for large gatherings. These people are not anti-maskers/anti-vaxxers and used to wear their masks. Due to unclear expectations set by the CDC, state governments, businesses, and peers, they no longer wear their mask.
I was going to go to a wedding this weekend, but I'm sure there will be a lot of Mouth-breathers at the event.
The shape a female mouth takes upon being informed of something she does not appreciate.
Yo that bitch had the meanest gash mouth when dan told her to suck him off.
To take your loved ones penis and cuddle it with your mouth in an act of felatio
"Come here Adam, I'm giving you a mouth cuddle for your birthday"
Used to imply retardicity or dumbassyness
*sees hayden's Sophie Wilson Mouth*
'Sophie has a scraggly ass mouth'