Top Definition
Undeserved Sense of Self Importance

When a person believes and acts as though they matter more than they actually do.
John A: I'm kind of a big deal.

John B: Wow, someone's got a serious case of the USSI.
by Neenerneenerbooboo November 02, 2010

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.