"coalmine" meaning in English

{
  "forms": [
    {
      "form": "coalmines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "coalmine (plural coalmines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "coal mine"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1983, William Hinton, “Two Dams and a Railroad”, in Shenfan, New York: Vintage Books, published 1984, →ISBN, →LCCN, →OCLC, page 226:",
          "text": "Work on the new railroad that thrust its way up onto the Shangtang: Plateau from the old railhead at the huge coalmine of Chiaotso in the Yellow River Valley went on for three years.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of coal mine."
      ],
      "id": "en-coalmine-en-noun-3~vRvuJl",
      "links": [
        [
          "coal mine",
          "coal mine#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "coalmine"
}

{
  "forms": [
    {
      "form": "coalmines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "coalmine (plural coalmines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "coal mine"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English nouns",
        "English terms with quotations",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "examples": [
        {
          "ref": "1983, William Hinton, “Two Dams and a Railroad”, in Shenfan, New York: Vintage Books, published 1984, →ISBN, →LCCN, →OCLC, page 226:",
          "text": "Work on the new railroad that thrust its way up onto the Shangtang: Plateau from the old railhead at the huge coalmine of Chiaotso in the Yellow River Valley went on for three years.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of coal mine."
      ],
      "links": [
        [
          "coal mine",
          "coal mine#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "coalmine"
}