"canary in the coal mine" meaning in English

{
  "forms": [
    {
      "form": "canaries in the coal mine",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "canaries in coal mines",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "canaries in the coal mines",
      "tags": [
        "plural"
      ]
    }
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        "1": "canaries in the coal mine",
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      "expansion": "canary in the coal mine (plural canaries in the coal mine or canaries in coal mines or canaries in the coal mines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "canary in a coal mine"
        }
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          "source": "w"
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      "examples": [
        {
          "ref": "2006, Al Gore, An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It, Rodale, →ISBN, page 176:",
          "text": "The second canary in the coal mine — along with the Arctic— is Antarctica, the largest mass of ice on the planet by far.",
          "type": "quote"
        },
        {
          "ref": "2007, Kentwood D. Wells, The Ecology and Behavior of Amphibians, The University of Chicago Press, →ISBN, pages 784–785:",
          "text": "Many authors state, almost as a truism, that amphibians are more vulnerable to environmental insults than are other vertebrates and therefore might serve as a kind of “canary in the coal mine,” an indicator of environmental degradation (e.g., Carroll 1999).",
          "type": "quote"
        },
        {
          "ref": "2009, Erica Manfred, He's History, You're Not: Surviving Divorce After 40, GPP Life, →ISBN, page 167:",
          "text": "Sex is the canary in the coal mine. It's the first thing to go when a marriage is in trouble.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of canary in a coal mine"
      ],
      "id": "en-canary_in_the_coal_mine-en-noun-AG2kZfOO",
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          "canary in a coal mine",
          "canary in a coal mine#English"
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  ],
  "word": "canary in the coal mine"
}

{
  "forms": [
    {
      "form": "canaries in the coal mine",
      "tags": [
        "plural"
      ]
    },
    {
      "form": "canaries in coal mines",
      "tags": [
        "plural"
      ]
    },
    {
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      "tags": [
        "plural"
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    }
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      "expansion": "canary in the coal mine (plural canaries in the coal mine or canaries in coal mines or canaries in the coal mines)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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          "word": "canary in a coal mine"
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      "examples": [
        {
          "ref": "2006, Al Gore, An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It, Rodale, →ISBN, page 176:",
          "text": "The second canary in the coal mine — along with the Arctic— is Antarctica, the largest mass of ice on the planet by far.",
          "type": "quote"
        },
        {
          "ref": "2007, Kentwood D. Wells, The Ecology and Behavior of Amphibians, The University of Chicago Press, →ISBN, pages 784–785:",
          "text": "Many authors state, almost as a truism, that amphibians are more vulnerable to environmental insults than are other vertebrates and therefore might serve as a kind of “canary in the coal mine,” an indicator of environmental degradation (e.g., Carroll 1999).",
          "type": "quote"
        },
        {
          "ref": "2009, Erica Manfred, He's History, You're Not: Surviving Divorce After 40, GPP Life, →ISBN, page 167:",
          "text": "Sex is the canary in the coal mine. It's the first thing to go when a marriage is in trouble.",
          "type": "quote"
        }
      ],
      "glosses": [
        "Alternative form of canary in a coal mine"
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  "word": "canary in the coal mine"
}