def /def/ adj. to describe a person, thing, or event that is cool. iarchaic, circa 1981/i
"yo, mah pizzles, I got da hook-up at this def new club. It's suppose ta be off da hizzy"
by Jay January 20, 2003
It means like terrific or great or excellent
"I bet you were def." ~Fresh Prince Of Bel Air when he's talking to Ashley about her singing. 1st episode
by Lady_Rae_Marie January 11, 2006
Def ain't short for Deffinitly.

Def means cool, ill, dope. You know.
Yo man Bone Thugs N Harmony are one of the most def groups of all time.
by some polak September 18, 2004
Can be short for definitely or definition. It can also be used to emphasize a word such as something is really cool or really not cool, etc.

(orgin well the celtic swim '06-07 team can take credit i guess)
Gouge Vomit Burn is the def. of sick nasty. (definition) That's def going to happen. (definitely) Are we going to have a dance party later? Yeah def!
by Celtic Swim '06-07 January 28, 2007
1. short for definitely
2. short for definition
3. death, misspelled
4. record label Def Jam
5. deaf, misspelled

and most importantly:
6. HOT, COOL, GREAT!!
That song is def man!!
by SyntaxE July 16, 2006
I always mispell the word definitely, so its easier to text def, than spend 5 minutes trying to fix the messed up word I get from T9 on my cell phone.
by caffeinequeen October 23, 2007
Short for definately, but often used sarcastically.
(Person A looking at a hot chick)

Person A: I think I have a chance with that babe.

Person B: Def dude.
by Matt0912 May 11, 2009