1 definition by xmasfox

Top Definition
A person, usually a woman, who avoids risque sexual activities, especially those involving a "backside" nature. The phrase derives from the tendency of functional groups attached to t-butyl to avoid participating in chemical reactions due to steric hindrance. Often affectionately abbreviated as t-but (pronounced t-buit).
Guy: Man that nun is hot!
Other Guy: Yea but I'm sure that she's a t-butyl!
by xmasfox March 23, 2008

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.