"double X" meaning in English

{
  "etymology_text": "From X, the Roman numeral representing 10.",
  "forms": [
    {
      "form": "double Xs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "double X"
      },
      "expansion": "double X (plural double Xs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Money",
          "orig": "en:Money",
          "parents": [
            "Business",
            "Economics",
            "Society",
            "Social sciences",
            "All topics",
            "Sciences",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1916, Jack Lait, “The Canada Kid” (chapter 9), in Beef, Iron and Wine, New York, N.Y.: Doubleday, Page & Company, pages 178–179:",
          "text": "“Hikes aroun’ wit’ a hundre’ an’ ninety bucks in ’is kick an’ won’t loosen a double X fer an ol’ frien’ what’s up again’ it? Why, dat guy ain’t got de firs’ idee about bein’ square wit’ a pal or librul wit’ an ol’ friend in de same line. An’—”",
          "type": "quote"
        }
      ],
      "glosses": [
        "Twenty dollars; a $20 bill."
      ],
      "id": "en-double_X-en-noun-TtKbhShl",
      "links": [
        [
          "Twenty",
          "twenty"
        ],
        [
          "dollar",
          "dollar"
        ],
        [
          "bill",
          "bill"
        ]
      ],
      "raw_glosses": [
        "(US, slang, dated) Twenty dollars; a $20 bill."
      ],
      "tags": [
        "US",
        "dated",
        "slang"
      ]
    }
  ],
  "word": "double X"
}

{
  "etymology_text": "From X, the Roman numeral representing 10.",
  "forms": [
    {
      "form": "double Xs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "head": "double X"
      },
      "expansion": "double X (plural double Xs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "American English",
        "English countable nouns",
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English slang",
        "English terms containing Roman numerals",
        "English terms with quotations",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Money"
      ],
      "examples": [
        {
          "ref": "1916, Jack Lait, “The Canada Kid” (chapter 9), in Beef, Iron and Wine, New York, N.Y.: Doubleday, Page & Company, pages 178–179:",
          "text": "“Hikes aroun’ wit’ a hundre’ an’ ninety bucks in ’is kick an’ won’t loosen a double X fer an ol’ frien’ what’s up again’ it? Why, dat guy ain’t got de firs’ idee about bein’ square wit’ a pal or librul wit’ an ol’ friend in de same line. An’—”",
          "type": "quote"
        }
      ],
      "glosses": [
        "Twenty dollars; a $20 bill."
      ],
      "links": [
        [
          "Twenty",
          "twenty"
        ],
        [
          "dollar",
          "dollar"
        ],
        [
          "bill",
          "bill"
        ]
      ],
      "raw_glosses": [
        "(US, slang, dated) Twenty dollars; a $20 bill."
      ],
      "tags": [
        "US",
        "dated",
        "slang"
      ]
    }
  ],
  "word": "double X"
}