"old franc" meaning in English

{
  "etymology_text": "Retronym for franc, to avoid confusion with the new franc.",
  "forms": [
    {
      "form": "old francs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "old franc (plural old francs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English retronyms",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "One French franc before January 1960, when it was devalued to 1/100 of its original value and replaced by the new franc, worth 100 old francs."
      ],
      "id": "en-old_franc-en-noun-fNNGvrCR",
      "links": [
        [
          "French franc",
          "French franc"
        ],
        [
          "new franc",
          "new franc"
        ]
      ],
      "raw_glosses": [
        "(historical) One French franc before January 1960, when it was devalued to 1/100 of its original value and replaced by the new franc, worth 100 old francs."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "old franc"
}

{
  "etymology_text": "Retronym for franc, to avoid confusion with the new franc.",
  "forms": [
    {
      "form": "old francs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "old franc (plural old francs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English retronyms",
        "English terms with historical senses",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "One French franc before January 1960, when it was devalued to 1/100 of its original value and replaced by the new franc, worth 100 old francs."
      ],
      "links": [
        [
          "French franc",
          "French franc"
        ],
        [
          "new franc",
          "new franc"
        ]
      ],
      "raw_glosses": [
        "(historical) One French franc before January 1960, when it was devalued to 1/100 of its original value and replaced by the new franc, worth 100 old francs."
      ],
      "tags": [
        "historical"
      ]
    }
  ],
  "word": "old franc"
}