Same meaning as "dunno", which comes from "don't know", except it's shorter and easier to type when IMing
by krystal_kiss February 17, 2006
Unno is the latest in a long line of Proper English words unwillingfully sodomised so that they are fit for internet consumption.
by jayseven July 28, 2004
A phrase most frequently used over the internet. This is a polite way of saying " I don't wanna do what you wanna do , so fuck off . "
by deanispenis November 11, 2009