"unknown" meaning in English

{
  "categories": [
    {
      "kind": "other",
      "name": "Terms prefixed with un-",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "un-",
        "2": "known"
      },
      "expansion": "un- + known",
      "name": "word parts"
    }
  ],
  "etymology_text": "un- + known",
  "forms": [
    {
      "form": "unknown",
      "tags": [
        "positive"
      ]
    },
    {
      "form": "more unknown",
      "tags": [
        "comparative"
      ]
    },
    {
      "form": "most unknown",
      "tags": [
        "superlative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "more": "true"
      },
      "expansion": "[POS TABLE]",
      "name": "adj"
    }
  ],
  "hyphenation": "un‧known",
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "examples": [
        {
          "text": "Nothing was written down, and it was a long time ago, so his true date of birth is unknown."
        }
      ],
      "glosses": [
        "If something is unknown, nobody knows it."
      ],
      "id": "simple-unknown-en-adj-6UHfXiO9"
    }
  ],
  "sounds": [
    {
      "ipa": "/ʌnˈnəʊn/",
      "tags": [
        "UK"
      ]
    },
    {
      "sampa": "/Vn\"n@Un/",
      "tags": [
        "UK"
      ]
    },
    {
      "enpr": "ŭn-nōnʹ",
      "tags": [
        "US"
      ]
    },
    {
      "ipa": "/ʌnˈnoʊn/",
      "tags": [
        "US"
      ]
    },
    {
      "sampa": "/Vn\"noUn/",
      "tags": [
        "US"
      ]
    },
    {
      "audio": "en-us-unknown.ogg",
      "raw_tags": [
        "Audio"
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "unknown"
}

{
  "categories": [
    "Terms prefixed with un-"
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "un-",
        "2": "known"
      },
      "expansion": "un- + known",
      "name": "word parts"
    }
  ],
  "etymology_text": "un- + known",
  "forms": [
    {
      "form": "unknown",
      "tags": [
        "positive"
      ]
    },
    {
      "form": "more unknown",
      "tags": [
        "comparative"
      ]
    },
    {
      "form": "most unknown",
      "tags": [
        "superlative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "more": "true"
      },
      "expansion": "[POS TABLE]",
      "name": "adj"
    }
  ],
  "hyphenation": "un‧known",
  "lang": "English",
  "lang_code": "en",
  "pos": "adj",
  "senses": [
    {
      "examples": [
        {
          "text": "Nothing was written down, and it was a long time ago, so his true date of birth is unknown."
        }
      ],
      "glosses": [
        "If something is unknown, nobody knows it."
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ʌnˈnəʊn/",
      "tags": [
        "UK"
      ]
    },
    {
      "sampa": "/Vn\"n@Un/",
      "tags": [
        "UK"
      ]
    },
    {
      "enpr": "ŭn-nōnʹ",
      "tags": [
        "US"
      ]
    },
    {
      "ipa": "/ʌnˈnoʊn/",
      "tags": [
        "US"
      ]
    },
    {
      "sampa": "/Vn\"noUn/",
      "tags": [
        "US"
      ]
    },
    {
      "audio": "en-us-unknown.ogg",
      "raw_tags": [
        "Audio"
      ],
      "tags": [
        "US"
      ]
    }
  ],
  "word": "unknown"
}