"hackday" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "hack",
        "3": "day"
      },
      "expansion": "hack + day",
      "name": "compound"
    }
  ],
  "etymology_text": "hack + day",
  "forms": [
    {
      "form": "hackdays",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hackday (plural hackdays)",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
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        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
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            "Entry maintenance"
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          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Computing",
          "orig": "en:Computing",
          "parents": [
            "Technology",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "The day when a hackathon is held."
      ],
      "id": "en-hackday-en-noun-EHHnpV0q",
      "links": [
        [
          "computing",
          "computing#Noun"
        ],
        [
          "hackathon",
          "hackathon"
        ]
      ],
      "raw_glosses": [
        "(computing, informal) The day when a hackathon is held."
      ],
      "tags": [
        "informal"
      ],
      "topics": [
        "computing",
        "engineering",
        "mathematics",
        "natural-sciences",
        "physical-sciences",
        "sciences"
      ]
    }
  ],
  "word": "hackday"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "hack",
        "3": "day"
      },
      "expansion": "hack + day",
      "name": "compound"
    }
  ],
  "etymology_text": "hack + day",
  "forms": [
    {
      "form": "hackdays",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "hackday (plural hackdays)",
      "name": "en-noun"
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  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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        "en:Computing"
      ],
      "glosses": [
        "The day when a hackathon is held."
      ],
      "links": [
        [
          "computing",
          "computing#Noun"
        ],
        [
          "hackathon",
          "hackathon"
        ]
      ],
      "raw_glosses": [
        "(computing, informal) The day when a hackathon is held."
      ],
      "tags": [
        "informal"
      ],
      "topics": [
        "computing",
        "engineering",
        "mathematics",
        "natural-sciences",
        "physical-sciences",
        "sciences"
      ]
    }
  ],
  "word": "hackday"
}