"鉄壁" meaning in Japanese

{
  "forms": [
    {
      "form": "鉄壁",
      "ruby": [
        [
          "鉄",
          "てっ"
        ],
        [
          "壁",
          "ぺき"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "teppeki",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "てっぺき"
      },
      "expansion": "鉄(てっ)壁(ぺき) • (teppeki)",
      "name": "ja-noun"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "kinjō teppeki, “an impregnable fortress”",
          "word": "金城鉄壁"
        }
      ],
      "categories": [
        {
          "_dis": "44 21 35",
          "kind": "other",
          "name": "Japanese terms with 2 kanji",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Clipping of 金城鉄壁 (kinjō teppeki, “an impregnable fortress”)."
      ],
      "id": "en-鉄壁-ja-noun-YUo4thbA",
      "links": [
        [
          "金城鉄壁",
          "金城鉄壁#Japanese"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "clipping"
      ]
    },
    {
      "glosses": [
        "an iron wall"
      ],
      "id": "en-鉄壁-ja-noun-hdKdHLRf",
      "links": [
        [
          "wall",
          "wall"
        ]
      ]
    },
    {
      "categories": [
        {
          "_dis": "32 2 66",
          "kind": "other",
          "name": "Japanese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "31 3 66",
          "kind": "other",
          "name": "Japanese links with redundant wikilinks",
          "parents": [
            "Links with redundant wikilinks",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "30 3 68",
          "kind": "other",
          "name": "Japanese terms with redundant sortkeys",
          "parents": [
            "Terms with redundant sortkeys",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "19 4 77",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "10 3 86",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "english": "impenetrable defenses",
          "roman": "teppeki no bōgyo",
          "ruby": [
            [
              "鉄壁",
              "てっぺき"
            ],
            [
              "防御",
              "ぼうぎょ"
            ]
          ],
          "text": "鉄壁の防御",
          "type": "example"
        }
      ],
      "glosses": [
        "impregnable, impenetrable, unshakeable"
      ],
      "id": "en-鉄壁-ja-noun-VeQASwCu",
      "links": [
        [
          "impregnable",
          "impregnable"
        ],
        [
          "impenetrable",
          "impenetrable"
        ],
        [
          "unshakeable",
          "unshakeable"
        ]
      ]
    }
  ],
  "word": "鉄壁"
}

{
  "categories": [
    "Japanese entries with incorrect language header",
    "Japanese lemmas",
    "Japanese links with redundant wikilinks",
    "Japanese nouns",
    "Japanese terms spelled with secondary school kanji",
    "Japanese terms spelled with third grade kanji",
    "Japanese terms with 2 kanji",
    "Japanese terms with redundant sortkeys",
    "Pages with 1 entry",
    "Pages with entries"
  ],
  "forms": [
    {
      "form": "鉄壁",
      "ruby": [
        [
          "鉄",
          "てっ"
        ],
        [
          "壁",
          "ぺき"
        ]
      ],
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "teppeki",
      "tags": [
        "romanization"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "てっぺき"
      },
      "expansion": "鉄(てっ)壁(ぺき) • (teppeki)",
      "name": "ja-noun"
    }
  ],
  "lang": "Japanese",
  "lang_code": "ja",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "kinjō teppeki, “an impregnable fortress”",
          "word": "金城鉄壁"
        }
      ],
      "categories": [
        "Japanese clippings"
      ],
      "glosses": [
        "Clipping of 金城鉄壁 (kinjō teppeki, “an impregnable fortress”)."
      ],
      "links": [
        [
          "金城鉄壁",
          "金城鉄壁#Japanese"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "clipping"
      ]
    },
    {
      "glosses": [
        "an iron wall"
      ],
      "links": [
        [
          "wall",
          "wall"
        ]
      ]
    },
    {
      "categories": [
        "Japanese terms with usage examples"
      ],
      "examples": [
        {
          "english": "impenetrable defenses",
          "roman": "teppeki no bōgyo",
          "ruby": [
            [
              "鉄壁",
              "てっぺき"
            ],
            [
              "防御",
              "ぼうぎょ"
            ]
          ],
          "text": "鉄壁の防御",
          "type": "example"
        }
      ],
      "glosses": [
        "impregnable, impenetrable, unshakeable"
      ],
      "links": [
        [
          "impregnable",
          "impregnable"
        ],
        [
          "impenetrable",
          "impenetrable"
        ],
        [
          "unshakeable",
          "unshakeable"
        ]
      ]
    }
  ],
  "word": "鉄壁"
}

{
  "called_from": "parser/1336",
  "msg": "no corresponding start tag found for </span>",
  "path": [
    "鉄壁"
  ],
  "section": "Japanese",
  "subsection": "noun",
  "title": "鉄壁",
  "trace": ""
}