"know one's stuff" meaning in English

{
  "antonyms": [
    {
      "word": "know one's ass from a hole in the ground"
    }
  ],
  "forms": [
    {
      "form": "knows one's stuff",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "knowing one's stuff",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "knew one's stuff",
      "tags": [
        "past"
      ]
    },
    {
      "form": "known one's stuff",
      "tags": [
        "participle",
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "know<,,knew,known> one's stuff"
      },
      "expansion": "know 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)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Danish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Finnish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with French translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with German translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Italian translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Polish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Turkish translations",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "Joe really knows his stuff when it comes to baseball.",
          "type": "example"
        },
        {
          "ref": "2020, Emmet Sweeney, The Theban Empire, volume 3, page 176:",
          "text": "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.",
          "type": "quote"
        }
      ],
      "glosses": [
        "To be knowledgeable about and competent at a particular subject or task."
      ],
      "id": "en-know_one's_stuff-en-verb-fWc4UV1Z",
      "links": [
        [
          "knowledgeable",
          "knowledgeable"
        ],
        [
          "competent",
          "competent"
        ],
        [
          "particular",
          "particular"
        ],
        [
          "subject",
          "subject"
        ],
        [
          "task",
          "task"
        ]
      ],
      "raw_glosses": [
        "(intransitive, informal) To be knowledgeable about and competent at a particular subject or task."
      ],
      "synonyms": [
        {
          "word": "know one's onions"
        },
        {
          "tags": [
            "vulgar"
          ],
          "word": "know one's shit"
        },
        {
          "word": "know one's way around"
        },
        {
          "word": "know the drill"
        },
        {
          "word": "know the score"
        },
        {
          "word": "know which end is up"
        }
      ],
      "tags": [
        "informal",
        "intransitive"
      ],
      "translations": [
        {
          "code": "da",
          "lang": "Danish",
          "sense": "be generally experienced and knowledgeable",
          "word": "kende sin vej rundt"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "sense": "be generally experienced and knowledgeable",
          "tags": [
            "imperfective"
          ],
          "word": "znać się na czymś"
        },
        {
          "code": "tr",
          "lang": "Turkish",
          "sense": "be generally experienced and knowledgeable",
          "word": "avucunun içi gibi bilmek"
        },
        {
          "code": "da",
          "lang": "Danish",
          "sense": "knowledgeable in a particular field",
          "word": "kunne sit kram"
        },
        {
          "code": "da",
          "lang": "Danish",
          "sense": "knowledgeable in a particular field",
          "word": "være velindsat"
        },
        {
          "code": "fi",
          "lang": "Finnish",
          "sense": "knowledgeable in a particular field",
          "word": "osata hommansa"
        },
        {
          "code": "fr",
          "lang": "French",
          "sense": "knowledgeable in a particular field",
          "word": "toucher sa bille"
        },
        {
          "code": "de",
          "lang": "German",
          "sense": "knowledgeable in a particular field",
          "word": "sich gut auskennen"
        },
        {
          "code": "de",
          "lang": "German",
          "sense": "knowledgeable in a particular field",
          "word": "gut Bescheid wissen"
        },
        {
          "code": "it",
          "lang": "Italian",
          "sense": "knowledgeable in a particular field",
          "word": "sapere il fatto proprio"
        }
      ]
    }
  ],
  "word": "know one's stuff"
}

{
  "antonyms": [
    {
      "word": "know one's ass from a hole in the ground"
    }
  ],
  "forms": [
    {
      "form": "knows one's stuff",
      "tags": [
        "present",
        "singular",
        "third-person"
      ]
    },
    {
      "form": "knowing one's stuff",
      "tags": [
        "participle",
        "present"
      ]
    },
    {
      "form": "knew one's stuff",
      "tags": [
        "past"
      ]
    },
    {
      "form": "known one's stuff",
      "tags": [
        "participle",
        "past"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "know<,,knew,known> one's stuff"
      },
      "expansion": "know 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)",
      "name": "en-verb"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "verb",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English informal terms",
        "English intransitive verbs",
        "English lemmas",
        "English multiword terms",
        "English terms with quotations",
        "English terms with usage examples",
        "English verbs",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Quotation templates to be cleaned",
        "Terms with Danish translations",
        "Terms with Finnish translations",
        "Terms with French translations",
        "Terms with German translations",
        "Terms with Italian translations",
        "Terms with Polish translations",
        "Terms with Turkish translations"
      ],
      "examples": [
        {
          "text": "Joe really knows his stuff when it comes to baseball.",
          "type": "example"
        },
        {
          "ref": "2020, Emmet Sweeney, The Theban Empire, volume 3, page 176:",
          "text": "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.",
          "type": "quote"
        }
      ],
      "glosses": [
        "To be knowledgeable about and competent at a particular subject or task."
      ],
      "links": [
        [
          "knowledgeable",
          "knowledgeable"
        ],
        [
          "competent",
          "competent"
        ],
        [
          "particular",
          "particular"
        ],
        [
          "subject",
          "subject"
        ],
        [
          "task",
          "task"
        ]
      ],
      "raw_glosses": [
        "(intransitive, informal) To be knowledgeable about and competent at a particular subject or task."
      ],
      "tags": [
        "informal",
        "intransitive"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "know one's onions"
    },
    {
      "tags": [
        "vulgar"
      ],
      "word": "know one's shit"
    },
    {
      "word": "know one's way around"
    },
    {
      "word": "know the drill"
    },
    {
      "word": "know the score"
    },
    {
      "word": "know which end is up"
    }
  ],
  "translations": [
    {
      "code": "da",
      "lang": "Danish",
      "sense": "be generally experienced and knowledgeable",
      "word": "kende sin vej rundt"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "sense": "be generally experienced and knowledgeable",
      "tags": [
        "imperfective"
      ],
      "word": "znać się na czymś"
    },
    {
      "code": "tr",
      "lang": "Turkish",
      "sense": "be generally experienced and knowledgeable",
      "word": "avucunun içi gibi bilmek"
    },
    {
      "code": "da",
      "lang": "Danish",
      "sense": "knowledgeable in a particular field",
      "word": "kunne sit kram"
    },
    {
      "code": "da",
      "lang": "Danish",
      "sense": "knowledgeable in a particular field",
      "word": "være velindsat"
    },
    {
      "code": "fi",
      "lang": "Finnish",
      "sense": "knowledgeable in a particular field",
      "word": "osata hommansa"
    },
    {
      "code": "fr",
      "lang": "French",
      "sense": "knowledgeable in a particular field",
      "word": "toucher sa bille"
    },
    {
      "code": "de",
      "lang": "German",
      "sense": "knowledgeable in a particular field",
      "word": "sich gut auskennen"
    },
    {
      "code": "de",
      "lang": "German",
      "sense": "knowledgeable in a particular field",
      "word": "gut Bescheid wissen"
    },
    {
      "code": "it",
      "lang": "Italian",
      "sense": "knowledgeable in a particular field",
      "word": "sapere il fatto proprio"
    }
  ],
  "word": "know one's stuff"
}