"empty letter" meaning in All languages combined

{
  "forms": [
    {
      "form": "empty letters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "empty letter (plural empty letters)",
      "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": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1979 April, Luis van Isschot, Pacificacion y Desarrollo: Clientelism, Community Kitchens, and the Articulation of Social Policy in Contemporary Peru:",
          "text": "\"According to Thorpe: 'The renewed social contract implied by the 1979 Constitution became virtually an empty letter.'”",
          "type": "quote"
        }
      ],
      "glosses": [
        "a promise that is not intended to be fulfilled"
      ],
      "id": "en-empty_letter-en-noun-axDoztVk"
    }
  ],
  "word": "empty letter"
}

{
  "forms": [
    {
      "form": "empty letters",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "empty letter (plural empty letters)",
      "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 terms with quotations",
        "Pages with 1 entry",
        "Pages with entries",
        "Quotation templates to be cleaned"
      ],
      "examples": [
        {
          "ref": "1979 April, Luis van Isschot, Pacificacion y Desarrollo: Clientelism, Community Kitchens, and the Articulation of Social Policy in Contemporary Peru:",
          "text": "\"According to Thorpe: 'The renewed social contract implied by the 1979 Constitution became virtually an empty letter.'”",
          "type": "quote"
        }
      ],
      "glosses": [
        "a promise that is not intended to be fulfilled"
      ]
    }
  ],
  "word": "empty letter"
}