"three-dog night" meaning in English

{
  "etymology_text": "An Eskimo saying, used to indicate a low temperature during the night, and when it is very cold, one would require three sled dogs in the igloo to keep oneself warm.",
  "forms": [
    {
      "form": "three-dog nights",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "three-dog night (plural three-dog nights)",
      "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"
        }
      ],
      "glosses": [
        "A very cold night."
      ],
      "id": "en-three-dog_night-en-noun-SCOPCEvz",
      "raw_glosses": [
        "(dated) A very cold night."
      ],
      "related": [
        {
          "word": "rafter snapper"
        }
      ],
      "synonyms": [
        {
          "word": "three dog night"
        }
      ],
      "tags": [
        "dated"
      ]
    }
  ],
  "word": "three-dog night"
}

{
  "etymology_text": "An Eskimo saying, used to indicate a low temperature during the night, and when it is very cold, one would require three sled dogs in the igloo to keep oneself warm.",
  "forms": [
    {
      "form": "three-dog nights",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "three-dog night (plural three-dog nights)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "rafter snapper"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns"
      ],
      "glosses": [
        "A very cold night."
      ],
      "raw_glosses": [
        "(dated) A very cold night."
      ],
      "tags": [
        "dated"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "three dog night"
    }
  ],
  "word": "three-dog night"
}