"iron heater" meaning in English

{
  "forms": [
    {
      "form": "iron heaters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "iron heater (plural iron heaters)",
      "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"
        }
      ],
      "examples": [
        {
          "ref": "1877, Mrs. Matthias, The Laundry Maid: Her Duties, and How to Perform Them, page 27",
          "text": "It is made hollow, as it has been said, the cavity containing an iron heater, which is plunged into the fire, and made red-hot, or nearly so, as often as the iron cools.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The piece of metal heated in the fire for a box iron."
      ],
      "id": "en-iron_heater-en-noun-5zy7viV1",
      "links": [
        [
          "metal",
          "metal"
        ],
        [
          "fire",
          "fire"
        ],
        [
          "box iron",
          "box iron"
        ]
      ],
      "raw_glosses": [
        "(historical) The piece of metal heated in the fire for a box iron."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "iron heater"
}

{
  "forms": [
    {
      "form": "iron heaters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "iron heater (plural iron heaters)",
      "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",
        "English terms with historical senses",
        "English terms with quotations",
        "Quotation templates to be cleaned"
      ],
      "examples": [
        {
          "ref": "1877, Mrs. Matthias, The Laundry Maid: Her Duties, and How to Perform Them, page 27",
          "text": "It is made hollow, as it has been said, the cavity containing an iron heater, which is plunged into the fire, and made red-hot, or nearly so, as often as the iron cools.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The piece of metal heated in the fire for a box iron."
      ],
      "links": [
        [
          "metal",
          "metal"
        ],
        [
          "fire",
          "fire"
        ],
        [
          "box iron",
          "box iron"
        ]
      ],
      "raw_glosses": [
        "(historical) The piece of metal heated in the fire for a box iron."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "iron heater"
}