"空洞" meaning in Japanese

{
  "forms": [
    {
      "form": "空洞",
      "ruby": [
        [
          "空",
          "くう"
        ],
        [
          "洞",
          "どう"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "kūdō",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "くうどう"
      },
      "expansion": "空(くう)洞(どう) • (kūdō)",
      "name": "ja-noun"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "_dis": "91 9",
          "kind": "other",
          "name": "Japanese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "96 4",
          "kind": "other",
          "name": "Japanese links with redundant wikilinks",
          "parents": [
            "Links with redundant wikilinks",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "96 4",
          "kind": "other",
          "name": "Japanese terms with redundant sortkeys",
          "parents": [
            "Terms with redundant sortkeys",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "english": "The inside of the flute was nothing more than the hollow of a piece of bamboo.",
          "ref": "1924, 小川未明, 赤い船のお客",
          "roman": "Fue no naka wa, tada ippon no kūdō no take ni shika sugimasen deshita.",
          "ruby": [
            [
              "笛",
              "ふえ"
            ],
            [
              "中",
              "なか"
            ],
            [
              "一本",
              "いっぽん"
            ],
            [
              "空洞",
              "くうどう"
            ],
            [
              "竹",
              "たけ"
            ]
          ],
          "text": "笛の中は、ただ一本の空洞の竹にしかすぎませんでした。"
        }
      ],
      "glosses": [
        "a hollow"
      ],
      "id": "en-空洞-ja-noun-ga8ZuVVn",
      "links": [
        [
          "hollow",
          "hollow"
        ]
      ]
    },
    {
      "glosses": [
        "cave"
      ],
      "id": "en-空洞-ja-noun-uJoZnqgb",
      "links": [
        [
          "cave",
          "cave"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[kɯ̟ᵝːdo̞ː]"
    }
  ],
  "word": "空洞"
}

{
  "categories": [
    "Japanese entries with incorrect language header",
    "Japanese lemmas",
    "Japanese links with redundant wikilinks",
    "Japanese nouns",
    "Japanese terms spelled with first grade kanji",
    "Japanese terms spelled with secondary school kanji",
    "Japanese terms with IPA pronunciation",
    "Japanese terms with redundant sortkeys",
    "Japanese terms written with two Han script characters"
  ],
  "forms": [
    {
      "form": "空洞",
      "ruby": [
        [
          "空",
          "くう"
        ],
        [
          "洞",
          "どう"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "kūdō",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "くうどう"
      },
      "expansion": "空(くう)洞(どう) • (kūdō)",
      "name": "ja-noun"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "Japanese terms with usage examples"
      ],
      "examples": [
        {
          "english": "The inside of the flute was nothing more than the hollow of a piece of bamboo.",
          "ref": "1924, 小川未明, 赤い船のお客",
          "roman": "Fue no naka wa, tada ippon no kūdō no take ni shika sugimasen deshita.",
          "ruby": [
            [
              "笛",
              "ふえ"
            ],
            [
              "中",
              "なか"
            ],
            [
              "一本",
              "いっぽん"
            ],
            [
              "空洞",
              "くうどう"
            ],
            [
              "竹",
              "たけ"
            ]
          ],
          "text": "笛の中は、ただ一本の空洞の竹にしかすぎませんでした。"
        }
      ],
      "glosses": [
        "a hollow"
      ],
      "links": [
        [
          "hollow",
          "hollow"
        ]
      ]
    },
    {
      "glosses": [
        "cave"
      ],
      "links": [
        [
          "cave",
          "cave"
        ]
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[kɯ̟ᵝːdo̞ː]"
    }
  ],
  "word": "空洞"
}