a person/animal/other organism that does actions/things that are unfavorable and seen by others as stupid, it's also an insult to a person who is pea-brained.
bosco:10+10 is not twenty it don't have ten in it!
Damien: bosco u fucking dumbass it doesn't need to have that to be twenty
Ben:seriously bosco, did you skip 1st grade or something?
By Phillis
Dumbass
A person is both stupid (e.g. dumb) while also stubbornly refusing to stop being stupid when asked (e.g. ass)
1. someone that is stupid 2. someone who spells out street talk so they think they sound cool
3. someone who thinks that they have it worse than everyone else
That guy is a dumbass.
The person whoe wrote, "I'm in da hizzouse 4 realz mo fo." is a dumbass.
The girl who is bitching about everything is a dumbass.