"footwall" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "foot",
        "3": "wall"
      },
      "expansion": "foot + wall",
      "name": "compound"
    }
  ],
  "etymology_text": "foot + wall",
  "forms": [
    {
      "form": "footwalls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "footwall (plural footwalls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Geology",
          "orig": "en:Geology",
          "parents": [
            "Earth sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "_dis": "80 20",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "The section of rock that extends below a diagonal fault line (the corresponding upper section being the hanging wall)."
      ],
      "id": "en-footwall-en-noun-rTVmvwpJ",
      "links": [
        [
          "geology",
          "geology"
        ],
        [
          "fault line",
          "fault line"
        ],
        [
          "hanging wall",
          "hanging wall"
        ]
      ],
      "raw_glosses": [
        "(geology) The section of rock that extends below a diagonal fault line (the corresponding upper section being the hanging wall)."
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    },
    {
      "categories": [
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Mining",
          "orig": "en:Mining",
          "parents": [
            "Industries",
            "Business",
            "Economics",
            "Society",
            "Social sciences",
            "All topics",
            "Sciences",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The under wall of an enclosed vein."
      ],
      "id": "en-footwall-en-noun-IGyUenC5",
      "links": [
        [
          "mining",
          "mining#Noun"
        ],
        [
          "vein",
          "vein"
        ]
      ],
      "raw_glosses": [
        "(mining) The under wall of an enclosed vein."
      ],
      "topics": [
        "business",
        "mining"
      ]
    }
  ],
  "word": "footwall"
}

{
  "categories": [
    "English compound terms",
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English nouns"
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "foot",
        "3": "wall"
      },
      "expansion": "foot + wall",
      "name": "compound"
    }
  ],
  "etymology_text": "foot + wall",
  "forms": [
    {
      "form": "footwalls",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "footwall (plural footwalls)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "en:Geology"
      ],
      "glosses": [
        "The section of rock that extends below a diagonal fault line (the corresponding upper section being the hanging wall)."
      ],
      "links": [
        [
          "geology",
          "geology"
        ],
        [
          "fault line",
          "fault line"
        ],
        [
          "hanging wall",
          "hanging wall"
        ]
      ],
      "raw_glosses": [
        "(geology) The section of rock that extends below a diagonal fault line (the corresponding upper section being the hanging wall)."
      ],
      "topics": [
        "geography",
        "geology",
        "natural-sciences"
      ]
    },
    {
      "categories": [
        "en:Mining"
      ],
      "glosses": [
        "The under wall of an enclosed vein."
      ],
      "links": [
        [
          "mining",
          "mining#Noun"
        ],
        [
          "vein",
          "vein"
        ]
      ],
      "raw_glosses": [
        "(mining) The under wall of an enclosed vein."
      ],
      "topics": [
        "business",
        "mining"
      ]
    }
  ],
  "word": "footwall"
}