1. The ultimate word that can describe anyone or anything. Can be used for describing how uninterested you are, your friends' personalities, music, the world, aliens, cafeteria food, etc.

2. What you name your pet when you can't think of a suitable name.
Dude1: Are you okay???
Dude2: derf...

Dude1: My friends are so awesome they're derf!

Dude2: Arg!!! This country's government is derf!

RandomLady: Let's name our new puppy... Derf!!!

RandomGirl: This is my pet hamster, Derf.
by Mio-chan July 10, 2008
A derf is another word for the unwanted. the person no one wants/need. the loner. the suspected pshyco killer. it can also be another word for tool, widely known as somebody no one needs (annoying). an extremely BIG insult.
Can you believe that effing Derf? what a tool!
by CoUnTrYwOrLd July 06, 2011
A person of unusual agility and skill.
I don't really want to play her. I hear she is a derf.
by 2forme November 12, 2007
A word used as a censor for the word "Fuck". Can be used in any tense that "Fuck" can.
What the derf is that?
May I please derf that bitch?
You are derfing insane, homie.
by Money Blimp January 25, 2010
another way to say the word "duh" almost like obviously
Person 1: Wait why are we going to the mall?
Person 2: To go shopping, derf!!!
by yeah3xyeah3xyeah3x March 11, 2011
Synonymous with a skilled ninja. Often used to describe a quick and fierce enemy who is extremely agile and deadly.
Person #1: There's that girl Sarah, lets go beat er' up.
Person #2: Fuck that! She's a derf! Im leaving her alone.
by Slimescree December 17, 2007
A bipolar vampire that is AWESOME!!!!!
1. I am not DERF.
2. You are such a DERF.
3. DERFs are so annoying but awesome at the same time.
by Zachary Max Zimmerman January 17, 2009

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