"crack of dawn" meaning in English

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      "form": "cracks of dawn",
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        "plural"
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      "expansion": "crack of dawn (plural cracks of dawn)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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          "kind": "topical",
          "langcode": "en",
          "name": "Times of day",
          "orig": "en:Times of day",
          "parents": [
            "Periodic occurrences",
            "Timekeeping",
            "Time",
            "All topics",
            "Fundamental"
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        }
      ],
      "derived": [
        {
          "word": "ass crack of dawn"
        },
        {
          "word": "butt crack of dawn"
        }
      ],
      "examples": [
        {
          "ref": "1985, Anne Tyler, chapter 20, in The Accidental Tourist, Knopf",
          "text": "\"This is high-speed travel, Muriel. Not fun. I'm waking up at crack of dawn.\"",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The first moment of daylight; before sunrise."
      ],
      "id": "en-crack_of_dawn-en-noun-uNxckH5u",
      "links": [
        [
          "daylight",
          "daylight"
        ],
        [
          "sunrise",
          "sunrise"
        ]
      ],
      "raw_glosses": [
        "(idiomatic) The first moment of daylight; before sunrise."
      ],
      "synonyms": [
        {
          "word": "daybreak"
        },
        {
          "word": "break of dawn"
        },
        {
          "tags": [
            "Commonwealth",
            "slang"
          ],
          "word": "sparrow-fart"
        },
        {
          "word": "dawn"
        }
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        "idiomatic"
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      "tags": [
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    }
  ],
  "word": "crack of dawn"
}

{
  "derived": [
    {
      "word": "ass crack of dawn"
    },
    {
      "word": "butt crack of dawn"
    }
  ],
  "forms": [
    {
      "form": "cracks of dawn",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
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      "expansion": "crack of dawn (plural cracks of dawn)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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        "en:Times of day"
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      "examples": [
        {
          "ref": "1985, Anne Tyler, chapter 20, in The Accidental Tourist, Knopf",
          "text": "\"This is high-speed travel, Muriel. Not fun. I'm waking up at crack of dawn.\"",
          "type": "quotation"
        }
      ],
      "glosses": [
        "The first moment of daylight; before sunrise."
      ],
      "links": [
        [
          "daylight",
          "daylight"
        ],
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          "sunrise",
          "sunrise"
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      "raw_glosses": [
        "(idiomatic) The first moment of daylight; before sunrise."
      ],
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      "tags": [
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  "synonyms": [
    {
      "word": "daybreak"
    },
    {
      "word": "break of dawn"
    },
    {
      "tags": [
        "Commonwealth",
        "slang"
      ],
      "word": "sparrow-fart"
    },
    {
      "word": "dawn"
    }
  ],
  "word": "crack of dawn"
}