'Deficient' - missing. Someone being diffy something will have lost of misplaced it. Usually a term related to and used by the British Army.
That soldier's diffy a pair of boots so he'll get billed for the loss.
by reme_critter July 18, 2011
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Adjective; a nickname or word used to describe a very adorable but stubborn boyfriend who knows his amazing girlfriend is right but is always being difficult at realizing this fact.
Girlfriend: Hey Baby! Look at this puppy it's so cute can we keep it?! I wanna name it Tyra <3

Boyfriend: No! We are not naming that dog Tyra. The only way that's happening is if that puppy is brown :)

Girlfriend: But I want a cute white puppy like this one! * shows pic

Boyfriend: no! The brown puppy or nuthin.

Girlfriend: ahhh fine you win Diffy. You're such a Diffy.
by Diffyluver69 April 30, 2012
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DIFFY: : lacking needful or desirable substance : weak, ineffectual.

Another word for: Retarded, Lame, Dumb, Boring, Stupid.
"Hey, dude. You going to Nate's party tonight?"

"I don't know, ,man. Last time I went over there it was pretty 'Diffy'."
by Metal Metal Rob Walsh August 28, 2010
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A person from the capital of Mexico. D.F. Districto Federal.
OMG did you see that diffy cross the border?
by Stephro February 22, 2009
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A diffy is a term people use when they are high on drugs (any kind) an have a sudden urge to lick a butthole.
Jones: Wow, these drugs are really making me want to do a diffy right now.
Slim: I agree.
by Barstars905 July 17, 2016
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