TTLY means "totally", which is usually used in msn lingo. this is commonly confused with TTYL which means "talk to you later".
by BigRigMerhe February 06, 2008
short-form for totally
by pr00t January 16, 2004
Commonly used on instant messaging, an abbreviation for "totally". Most often misread and mistaken for ttyl.
by smurph July 30, 2006