Top Definition
A temporary reduction in mental capacity due to having recently run several miles.
After my run yesterday, I spent half an hour wandering around the grocery store trying to decide what to eat for dinner, only to remember that I had just gone to the grocery store that morning. So then I went to In-n-Out. I think I'm coming down with a case of Runner's Brain.
by An Avid Runner April 08, 2013
Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from We'll never spam you.