Top Definition
A natural Vitamin B supplement. Often taken to flush THC out of the body.
Dude, I have to go buy some Niacin so I can pass the drug test at Target.
by KevinStrudz May 22, 2011

Free Daily Email

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

Emails are sent from daily@urbandictionary.com. We'll never spam you.

×