"core day" meaning in English

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      "expansion": "core day (plural core days)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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      "coordinate_terms": [
        {
          "word": "list in leg day"
        }
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      "examples": [
        {
          "ref": "2021 August 17, Morit Summers, Big & Bold: Strength Training for the Plus-Size Woman, Human Kinetics, →ISBN, page 147:",
          "text": "... leg day, back day, and core day.",
          "type": "quote"
        },
        {
          "ref": "2022 November 24, Kenneth Kollasch, Beating Average: A Story to Extraordinary, WestBow Press, →ISBN:",
          "text": "... leg day, cardio day, core day, chest day, and all the rest! But, have you ever taken a day to workout your tongue? We all know communication is vital to success in anything, and it is literally life or death when it comes to warfare[…]",
          "type": "quote"
        }
      ],
      "glosses": [
        "A day dedicated to exercising one's core."
      ],
      "id": "en-core_day-en-noun-5o3OJ2jI",
      "links": [
        [
          "exercising",
          "exercise"
        ]
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  "word": "core day"
}

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    {
      "word": "list in leg day"
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    {
      "form": "core days",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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      "examples": [
        {
          "ref": "2021 August 17, Morit Summers, Big & Bold: Strength Training for the Plus-Size Woman, Human Kinetics, →ISBN, page 147:",
          "text": "... leg day, back day, and core day.",
          "type": "quote"
        },
        {
          "ref": "2022 November 24, Kenneth Kollasch, Beating Average: A Story to Extraordinary, WestBow Press, →ISBN:",
          "text": "... leg day, cardio day, core day, chest day, and all the rest! But, have you ever taken a day to workout your tongue? We all know communication is vital to success in anything, and it is literally life or death when it comes to warfare[…]",
          "type": "quote"
        }
      ],
      "glosses": [
        "A day dedicated to exercising one's core."
      ],
      "links": [
        [
          "exercising",
          "exercise"
        ]
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  "word": "core day"
}