Someone that gets dirt on their back from riding too fast on a motorbike.
Erik had a dirtback from riding too fast on the trail.
by G Rider 80 March 16, 2010
3 more definitions
The after effects of debris (mud / dirt) on riding gear (primarily on their backs) after a long day of dirtbike riding.
I saw 4 dirtbacks climbing a very steep hill on their dirtbikes.
by Mike Hoss March 30, 2010
A person that brings dirt back on their shirt. Most likely caused by a long day riding bikes in the woods.
Did you see Joe's shirt, he tore it up in the woods today. He is such a Dirt Back.
by G Rider 80 April 06, 2010
Goddam dirtback, your mangy pit bull shat on my lawn again!
by Octopod November 08, 2003