def

¹ American  

[def] / dɛf /

adverb

Informal.

1. definitely.

   Going to Europe this summer? But def!

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def ² American  

[def] / dɛf /

adjective

1. Slang. excellent.

   That hip-hop record is def!

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def. ³ American  

abbreviation

1. defective.

2. defendant.

3. defense.

4. deferred.

5. defined.

6. definite.

7. definition.

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def. ¹ British  

abbreviation

1. definition

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def ² British  

/ dɛf /

adjective

1. slang very good, esp of hip-hop

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Etymology

Origin of def¹

By shortening

Origin of def²

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

Example Sentences

"If you're looking for a mental break from the world def get Pokopia, it's like therapy," US-based influencer Ashley Duncan wrote on X.

From Barron's • Mar. 11, 2026

“I def had a miscarriage on SSRI’s, too,” Banks wrote before encouraging her latest social media adversary to “get off the SSRI’s period.”

From Los Angeles Times • May 8, 2025

The liaison office is the def facto representative of Beijing in Hong Kong, which, since handover from Britain to China in 1997, has been run as a Special Administrative Region, or SAR.

From Washington Times • Dec. 11, 2023

There’s an intimacy to a book that we can’t get from a movie or a TV show, no matter how true it is — even in 3-D, in the highest of high def.

From New York Times • Apr. 27, 2023

“Oh, yes! I want to def —” He ignored her outburst.

From "Gathering Blue" by Lois Lowry