"S4C" meaning in Welsh

{
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "S4C f (not mutable)",
      "name": "cy-proper noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "name",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "a Welsh-language television network",
          "word": "Sianel Pedwar Cymru"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Welsh entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "Initialism of Sianel Pedwar Cymru; a Welsh-language television network."
      ],
      "id": "en-S4C-cy-name-i6UAgPdM",
      "links": [
        [
          "Sianel Pedwar Cymru",
          "Sianel Pedwar Cymru#Welsh"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "feminine",
        "initialism",
        "not-mutable"
      ],
      "wikipedia": [
        "cy:S4C"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˌɛs ˌpɛdwar ˈɛk/"
    },
    {
      "ipa": "/ˌɛsbɛdwar ˈɛk/"
    }
  ],
  "word": "S4C"
}

{
  "head_templates": [
    {
      "args": {
        "1": "f"
      },
      "expansion": "S4C f (not mutable)",
      "name": "cy-proper noun"
    }
  ],
  "lang": "Welsh",
  "lang_code": "cy",
  "pos": "name",
  "senses": [
    {
      "alt_of": [
        {
          "extra": "a Welsh-language television network",
          "word": "Sianel Pedwar Cymru"
        }
      ],
      "categories": [
        "Welsh entries with incorrect language header",
        "Welsh feminine nouns",
        "Welsh initialisms",
        "Welsh lemmas",
        "Welsh non-mutable terms",
        "Welsh proper nouns",
        "Welsh terms spelled with numbers",
        "Welsh terms with IPA pronunciation"
      ],
      "glosses": [
        "Initialism of Sianel Pedwar Cymru; a Welsh-language television network."
      ],
      "links": [
        [
          "Sianel Pedwar Cymru",
          "Sianel Pedwar Cymru#Welsh"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "feminine",
        "initialism",
        "not-mutable"
      ],
      "wikipedia": [
        "cy:S4C"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˌɛs ˌpɛdwar ˈɛk/"
    },
    {
      "ipa": "/ˌɛsbɛdwar ˈɛk/"
    }
  ],
  "word": "S4C"
}