"iron mould" meaning in English

{
  "forms": [
    {
      "form": "iron mold",
      "tags": [
        "alternative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "iron mould",
      "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"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Iron",
          "orig": "en:Iron",
          "parents": [
            "Transition metals",
            "Chemical elements",
            "Metals",
            "Matter",
            "Metallurgy",
            "Chemistry",
            "Nature",
            "Technology",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The yellow discoloration of cloth by rusty iron."
      ],
      "id": "en-iron_mould-en-noun-ev0UmtNj",
      "links": [
        [
          "yellow",
          "yellow"
        ],
        [
          "discoloration",
          "discoloration"
        ],
        [
          "cloth",
          "cloth"
        ],
        [
          "rusty",
          "rusty"
        ],
        [
          "iron",
          "iron"
        ]
      ]
    }
  ],
  "word": "iron mould"
}

{
  "forms": [
    {
      "form": "iron mold",
      "tags": [
        "alternative"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "iron mould",
      "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 nouns with unknown or uncertain plurals",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Iron"
      ],
      "glosses": [
        "The yellow discoloration of cloth by rusty iron."
      ],
      "links": [
        [
          "yellow",
          "yellow"
        ],
        [
          "discoloration",
          "discoloration"
        ],
        [
          "cloth",
          "cloth"
        ],
        [
          "rusty",
          "rusty"
        ],
        [
          "iron",
          "iron"
        ]
      ]
    }
  ],
  "word": "iron mould"
}