"post mill" meaning in English

{
  "forms": [
    {
      "form": "post mills",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "post mill (plural post mills)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "hollow post mill"
        }
      ],
      "glosses": [
        "A form of windmill constructed so that the whole building rests on a vertical axis firmly fastened to the ground. It is capable of being turned as the direction of the wind varies."
      ],
      "id": "en-post_mill-en-noun-SmqQ7ccg",
      "links": [
        [
          "windmill",
          "windmill"
        ]
      ]
    }
  ],
  "word": "post mill"
}

{
  "derived": [
    {
      "word": "hollow post mill"
    }
  ],
  "forms": [
    {
      "form": "post mills",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "post mill (plural post mills)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns"
      ],
      "glosses": [
        "A form of windmill constructed so that the whole building rests on a vertical axis firmly fastened to the ground. It is capable of being turned as the direction of the wind varies."
      ],
      "links": [
        [
          "windmill",
          "windmill"
        ]
      ]
    }
  ],
  "word": "post mill"
}