"3,14" meaning in Conventions internationales

{
  "categories": [
    {
      "kind": "other",
      "name": "Symboles en conventions internationales",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Conventions internationales",
      "orig": "conventions internationales",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "(Mathématiques) Troncature de la valeur décimale de π en ne prenant compte que de l’unité et de ses 2 premières décimales."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "related": [
    {
      "word": "π"
    },
    {
      "word": "3,14159265358979"
    },
    {
      "word": "3,1416"
    },
    {
      "sense": "Approximation de Liu Hui",
      "word": "22/7"
    },
    {
      "sense": "Approximation de Zu Chongzi",
      "word": "355/113"
    }
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Lexique en conventions internationales des mathématiques",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Troncature approximative de la valeur de π."
      ],
      "id": "fr-3,14-conv-symbol-o3oEWlFf",
      "topics": [
        "mathematics"
      ]
    }
  ],
  "word": "3,14"
}

{
  "categories": [
    "Symboles en conventions internationales",
    "conventions internationales"
  ],
  "etymology_texts": [
    "(Mathématiques) Troncature de la valeur décimale de π en ne prenant compte que de l’unité et de ses 2 premières décimales."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "related": [
    {
      "word": "π"
    },
    {
      "word": "3,14159265358979"
    },
    {
      "word": "3,1416"
    },
    {
      "sense": "Approximation de Liu Hui",
      "word": "22/7"
    },
    {
      "sense": "Approximation de Zu Chongzi",
      "word": "355/113"
    }
  ],
  "senses": [
    {
      "categories": [
        "Lexique en conventions internationales des mathématiques"
      ],
      "glosses": [
        "Troncature approximative de la valeur de π."
      ],
      "topics": [
        "mathematics"
      ]
    }
  ],
  "word": "3,14"
}