"C3" meaning in French

{
  "etymology_text": "From Coupe 1 (“Cup 1”), because was the third more important football competition in Europe, at the time of its creation. Since 2000 its it the second most important competition in Europe, after the UEFA Cup Winners' Cup (1960-1999) disappeared. Despite the demise of the UEFA Cup Winners' Cup, the UEFA Europa League retains the C3 name.",
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "C3 f",
      "name": "fr-proper noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "name",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "French entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "French metonyms",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 3 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "the UEFA Europa League (formerly the UEFA Cup (1971-2009))"
      ],
      "id": "en-C3-fr-name-U19oJIwh",
      "related": [
        {
          "word": "C1"
        },
        {
          "word": "C2"
        },
        {
          "word": "C4"
        }
      ],
      "synonyms": [
        {
          "word": "Ligue Europa"
        }
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "UEFA Cup Winners' Cup",
        "fr:C3"
      ]
    }
  ],
  "word": "C3"
}

{
  "etymology_text": "From Coupe 1 (“Cup 1”), because was the third more important football competition in Europe, at the time of its creation. Since 2000 its it the second most important competition in Europe, after the UEFA Cup Winners' Cup (1960-1999) disappeared. Despite the demise of the UEFA Cup Winners' Cup, the UEFA Europa League retains the C3 name.",
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "C3 f",
      "name": "fr-proper noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "name",
  "related": [
    {
      "word": "C1"
    },
    {
      "word": "C2"
    },
    {
      "word": "C4"
    }
  ],
  "senses": [
    {
      "categories": [
        "French entries with incorrect language header",
        "French feminine nouns",
        "French lemmas",
        "French metonyms",
        "French proper nouns",
        "French terms spelled with numbers",
        "Pages with 3 entries",
        "Pages with entries"
      ],
      "glosses": [
        "the UEFA Europa League (formerly the UEFA Cup (1971-2009))"
      ],
      "synonyms": [
        {
          "word": "Ligue Europa"
        }
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "UEFA Cup Winners' Cup",
        "fr:C3"
      ]
    }
  ],
  "word": "C3"
}