"Jour J" meaning in French

{
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "jour",
        "3": "J"
      },
      "expansion": "jour + J",
      "name": "af"
    },
    {
      "args": {
        "1": "fr",
        "2": "en",
        "3": "D-Day"
      },
      "expansion": "Calque of English D-Day",
      "name": "calque"
    }
  ],
  "etymology_text": "From jour + J.\nFrom J for jour (“day”).\nCalque of English D-Day, from D + day, D itself standing for day.\nFrom U.S. military terminology.",
  "head_templates": [
    {
      "args": {
        "1": "m",
        "head": "Jour J"
      },
      "expansion": "Jour J m",
      "name": "fr-proper noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "name",
  "senses": [
    {
      "categories": [
        {
          "_dis": "56 44",
          "kind": "other",
          "name": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "84 16",
          "kind": "topical",
          "langcode": "fr",
          "name": "World War II",
          "orig": "fr:World War II",
          "parents": [
            "Historical events",
            "History of Europe",
            "War",
            "History",
            "Europe",
            "Conflict",
            "Military",
            "Violence",
            "All topics",
            "Earth",
            "Eurasia",
            "Human behaviour",
            "Society",
            "Fundamental",
            "Nature",
            "Human"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "D-Day (“6 June 1944”) (WWII)"
      ],
      "id": "en-Jour_J-fr-name-LYO382sJ",
      "links": [
        [
          "D-Day",
          "D-Day#French"
        ]
      ],
      "tags": [
        "masculine"
      ]
    },
    {
      "glosses": [
        "The date of any major event planned for the future."
      ],
      "id": "en-Jour_J-fr-name-oqfJ3uLh",
      "raw_glosses": [
        "(figuratively) The date of any major event planned for the future."
      ],
      "tags": [
        "figuratively",
        "masculine"
      ]
    }
  ],
  "word": "Jour J"
}

{
  "categories": [
    "French compound terms",
    "French entries with incorrect language header",
    "French lemmas",
    "French masculine nouns",
    "French multiword terms",
    "French proper nouns",
    "French terms calqued from English",
    "French terms derived from English",
    "fr:World War II"
  ],
  "etymology_templates": [
    {
      "args": {
        "1": "fr",
        "2": "jour",
        "3": "J"
      },
      "expansion": "jour + J",
      "name": "af"
    },
    {
      "args": {
        "1": "fr",
        "2": "en",
        "3": "D-Day"
      },
      "expansion": "Calque of English D-Day",
      "name": "calque"
    }
  ],
  "etymology_text": "From jour + J.\nFrom J for jour (“day”).\nCalque of English D-Day, from D + day, D itself standing for day.\nFrom U.S. military terminology.",
  "head_templates": [
    {
      "args": {
        "1": "m",
        "head": "Jour J"
      },
      "expansion": "Jour J m",
      "name": "fr-proper noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "name",
  "senses": [
    {
      "glosses": [
        "D-Day (“6 June 1944”) (WWII)"
      ],
      "links": [
        [
          "D-Day",
          "D-Day#French"
        ]
      ],
      "tags": [
        "masculine"
      ]
    },
    {
      "glosses": [
        "The date of any major event planned for the future."
      ],
      "raw_glosses": [
        "(figuratively) The date of any major event planned for the future."
      ],
      "tags": [
        "figuratively",
        "masculine"
      ]
    }
  ],
  "word": "Jour J"
}