Dictionary.com
Thesaurus.com

deadass

American  
[ded-as] / ˈdɛdˌæs /

adverb

Slang.
  1. genuinely, sincerely, or truly; in fact: This deadass made me laugh in the grocery store.

    I'm deadass about to quote that speech to you.

    This deadass made me laugh in the grocery store.

  2. very or extremely: I'm deadass scared of clowns.

    I thought this was going to be a one-time thing, but I was deadass wrong.

    I'm deadass scared of clowns.


adjective

Slang.
  1. sincere or serious.

    There's no school today, I'm deadass.

interjection

Slang.
  1. (used to request confirmation of truth or to express surprise).

    “The new album's dropping tomorrow.” “Deadass?”

Etymology

Origin of deadass

First recorded in 1960–65; dead ( def. ) (in the adverbial sense “completely”) + -ass ( def. )

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.

She went on to say she supported Sea World and the Iraq War, was responsible for the Deepwater Horizon oil spill and wasn’t very smart: “I’ll deadass bite a worm on a hook,” she said.

From New York Times

“I have diagnosed tourettes. I’ve never mentioned it on the internet because nobody thinks I’m deadass,” the “Ocean Eyes” singer wrote in an Instagram story.

From Los Angeles Times

And with what she’s done with her portfolio, she tells the filmmakers, “I know I’m set for life. I just have to hold it. Deadass.”

From The Verge

“Deadass thought I made it obvious,” he wrote, accompanied by a deluge of rainbow emojis.

From The Guardian

His deadpan caption reads, “deadass thought i made it obvious.”

From Salon