"coffer-dam" meaning in English

{
  "forms": [
    {
      "form": "coffer-dams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "coffer-dam (plural coffer-dams)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "cofferdam"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1949 November and December, “Notes and News: The High Level Bridge, Newcastle: Strengthening and Repairs”, in Railway Magazine, page 407",
          "text": "Owing to the war, it was not thought advisable to carry out repairs to this pier, as this would have involved the temporary narrowing of the channel, and it was not until 1919 that it was decided to proceed with the construction of a steel-pile coffer dam round the south pier.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative spelling of cofferdam"
      ],
      "id": "en-coffer-dam-en-noun-mFkPZZ0~",
      "links": [
        [
          "cofferdam",
          "cofferdam#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "coffer-dam"
}

{
  "forms": [
    {
      "form": "coffer-dams",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "coffer-dam (plural coffer-dams)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "cofferdam"
        }
      ],
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1949 November and December, “Notes and News: The High Level Bridge, Newcastle: Strengthening and Repairs”, in Railway Magazine, page 407",
          "text": "Owing to the war, it was not thought advisable to carry out repairs to this pier, as this would have involved the temporary narrowing of the channel, and it was not until 1919 that it was decided to proceed with the construction of a steel-pile coffer dam round the south pier.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "Alternative spelling of cofferdam"
      ],
      "links": [
        [
          "cofferdam",
          "cofferdam#English"
        ]
      ],
      "tags": [
        "alt-of",
        "alternative"
      ]
    }
  ],
  "word": "coffer-dam"
}