"C2" meaning in French

{
  "etymology_text": "From Coupe 2 (“Cup 2”), because was the second more important football competition in Europe.",
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "C2 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 2 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "the defunct UEFA Cup Winners' Cup (1960-1999)"
      ],
      "id": "en-C2-fr-name-MlkgvDb7",
      "related": [
        {
          "word": "C1"
        },
        {
          "word": "C3"
        },
        {
          "word": "C4"
        }
      ],
      "synonyms": [
        {
          "word": "CVC"
        },
        {
          "word": "Coupe d'Europe des vainqueurs de coupe de football"
        },
        {
          "word": "Coupe des coupes"
        }
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "fr:C2"
      ]
    }
  ],
  "word": "C2"
}

{
  "etymology_text": "From Coupe 2 (“Cup 2”), because was the second more important football competition in Europe.",
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "C2 f",
      "name": "fr-proper noun"
    }
  ],
  "lang": "French",
  "lang_code": "fr",
  "pos": "name",
  "related": [
    {
      "word": "C1"
    },
    {
      "word": "C3"
    },
    {
      "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 2 entries",
        "Pages with entries"
      ],
      "glosses": [
        "the defunct UEFA Cup Winners' Cup (1960-1999)"
      ],
      "synonyms": [
        {
          "word": "CVC"
        },
        {
          "word": "Coupe d'Europe des vainqueurs de coupe de football"
        },
        {
          "word": "Coupe des coupes"
        }
      ],
      "tags": [
        "feminine"
      ],
      "wikipedia": [
        "fr:C2"
      ]
    }
  ],
  "word": "C2"
}