know one's stuff

verb

To be knowledgeable about and competent at a particular subject or task.

“Joe really knows his stuff when it comes to baseball.”

Similar
know ballknow one's onionsknow one's shitknow one's way aroundknow the drillknow the scoreknow which end is up
Opposite
know one's ass from a hole in the ground
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Meanings

verbknow one's stuff (third-person singular simple present knows one's stuff, present participle knowing one's stuff, simple past knew one's stuff, past participle known one's stuff)

present singular third person knows one's stuff · participle present knowing one's stuff · past knew one's stuff · participle past known one's stuff

  1. informalintransitiveTo be knowledgeable about and competent at a particular subject or task.

    Joe really knows his stuff when it comes to baseball.

    1 more example

    The field of knowledge in which Hori claimed to be an authority was Palestinology. The contents of the missive show that Hori certainly knew his stuff.

    2020, Emmet Sweeney, The Theban Empire, volume 3, page 176

    Synonyms: know ball, know one's onions, know one's shit, know one's way around, know the drill, know the score, know which end is up

Synonyms & antonyms

verbTo be knowledgeable about and competent at a particular subject or task.

Similar
know ballknow one's onionsknow one's shitknow one's way aroundknow the drillknow the scoreknow which end is up
Opposite
know one's ass from a hole in the ground
Also see
know ballknow one's onionsknow one's shitknow one's way around

Translations

Danish kende sin vej rundt, kunne sit kram
  • kende sin vej rundtbe generally experienced and knowledgeable
  • kunne sit kramknowledgeable in a particular field
  • være velindsatknowledgeable in a particular field
Finnish osata hommansa
  • osata hommansaknowledgeable in a particular field
French toucher sa bille
  • toucher sa billeknowledgeable in a particular field
German auskennen, gut Bescheid wissen
  • auskennenbe generally experienced and knowledgeable
  • gut Bescheid wissenbe generally experienced and knowledgeable
  • Ahnung habenbe generally experienced and knowledgeable
  • sich gut auskennenknowledgeable in a particular field
  • gut Bescheid wissenknowledgeable in a particular field
Italian sapere il fatto proprio
  • sapere il fatto proprioknowledgeable in a particular field
Polish znać się na czymś, znać się na rzeczy
  • znać się na czymśbe generally experienced and knowledgeable
  • znać się na rzeczyknowledgeable in a particular field
Turkish avucunun içi gibi bilmek
  • avucunun içi gibi bilmekbe generally experienced and knowledgeable
Cite this entry
APA

know one's stuff. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/know%20one's%20stuff

MLA

“know one's stuff.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/know%20one's%20stuff. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “know one's stuff,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/know%20one's%20stuff.

Source: know one's stuff on Wiktionary, CC BY-SA 4.0.