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def

1 American  
[def] / dɛf /

adverb

Informal.
  1. definitely.

    Going to Europe this summer? But def!


def 2 American  
[def] / dɛf /

adjective

  1. Slang.  excellent.

    That hip-hop record is def!


def. 3 American  

abbreviation

  1. defective.

  2. defendant.

  3. defense.

  4. deferred.

  5. defined.

  6. definite.

  7. definition.


def. 1 British  

abbreviation

  1. definition

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

def 2 British  
/ dɛf /

adjective

  1. slang  very good, esp of hip-hop

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of def1

By shortening

Origin of def2

An Americanism dating back to 1980–85; of uncertain origin

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

So the majority of the people that I know I met through All Def.

From Los Angeles Times

The credits of the track mention Aubierre Rivaldo Taylor as the songwriter -- a name that only appears online in association with the group Def Beats AI, which is clearly identified as an AI project.

From Barron's

Def Leppard's Vivian Campbell has revealed while performing in certain parts of Northern Ireland during the Troubles he would "shut up" on stage.

From BBC

Campbell joined Def Leppard in the early 1990s.

From BBC

Though streaming services like Spotify and Apple Music didn’t immediately publish the album’s credits, a press release from Bieber’s label Def Jam said he made “Swag II” with much of the same team behind “Swag,” including Carter Lang, Dylan Wiggins, Dijon, Mk.gee,

From Los Angeles Times