"!!" meaning in Conventions internationales

{
  "categories": [
    {
      "kind": "other",
      "name": "Palindromes en conventions internationales",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Symboles en conventions internationales",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Conventions internationales",
      "orig": "conventions internationales",
      "parents": [],
      "source": "w"
    }
  ],
  "derived": [
    {
      "raw_tags": [
        "Mathématiques"
      ],
      "word": "!"
    },
    {
      "raw_tags": [
        "Aux échecs"
      ],
      "word": "!?"
    },
    {
      "raw_tags": [
        "Aux échecs"
      ],
      "word": "?!"
    }
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Exemples en conventions internationales",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Exemples en conventions internationales avec traduction désactivée",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Lexique en conventions internationales des mathématiques",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "6!! = 6×4×2 = 48"
        },
        {
          "text": "5!! = 5×3×1 = 15"
        }
      ],
      "glosses": [
        "Symbole de la double factorielle."
      ],
      "id": "fr-!!-conv-symbol-nlKJ0~je",
      "raw_tags": [
        "Postposé"
      ],
      "topics": [
        "mathematics"
      ]
    },
    {
      "categories": [
        {
          "kind": "other",
          "name": "Lexique en conventions internationales des échecs",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Indique un très bon coup."
      ],
      "id": "fr-!!-conv-symbol-SXcwXWwa",
      "topics": [
        "chess"
      ]
    }
  ],
  "word": "!!"
}

{
  "categories": [
    "Palindromes en conventions internationales",
    "Symboles en conventions internationales",
    "conventions internationales"
  ],
  "derived": [
    {
      "raw_tags": [
        "Mathématiques"
      ],
      "word": "!"
    },
    {
      "raw_tags": [
        "Aux échecs"
      ],
      "word": "!?"
    },
    {
      "raw_tags": [
        "Aux échecs"
      ],
      "word": "?!"
    }
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "senses": [
    {
      "categories": [
        "Exemples en conventions internationales",
        "Exemples en conventions internationales avec traduction désactivée",
        "Lexique en conventions internationales des mathématiques"
      ],
      "examples": [
        {
          "text": "6!! = 6×4×2 = 48"
        },
        {
          "text": "5!! = 5×3×1 = 15"
        }
      ],
      "glosses": [
        "Symbole de la double factorielle."
      ],
      "raw_tags": [
        "Postposé"
      ],
      "topics": [
        "mathematics"
      ]
    },
    {
      "categories": [
        "Lexique en conventions internationales des échecs"
      ],
      "glosses": [
        "Indique un très bon coup."
      ],
      "topics": [
        "chess"
      ]
    }
  ],
  "word": "!!"
}