"back number" meaning in English

{
  "forms": [
    {
      "form": "back numbers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "back number (plural back numbers)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "_dis": "93 7",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "94 6",
          "kind": "other",
          "name": "English entries with topic categories using raw markup",
          "parents": [
            "Entries with topic categories using raw markup",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "89 11",
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "89 11",
          "kind": "topical",
          "langcode": "en",
          "name": "Periodicals",
          "orig": "en:Periodicals",
          "parents": [
            "Literature",
            "Mass media",
            "Culture",
            "Entertainment",
            "Writing",
            "Media",
            "Society",
            "Human behaviour",
            "Language",
            "Communication",
            "All topics",
            "Human",
            "Fundamental"
          ],
          "source": "w+disamb"
        }
      ],
      "examples": [
        {
          "ref": "1941 December, “Back Numbers of \"The Railway Magazine\"”, in Railway Magazine, page 574",
          "text": "Because of war conditions and rigid paper control, it is now impossible for us to keep supplies of recent back numbers.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A back issue of a magazine, etc."
      ],
      "id": "en-back_number-en-noun-zbUX2XIr",
      "links": [
        [
          "back issue",
          "back issue"
        ],
        [
          "magazine",
          "magazine"
        ]
      ],
      "synonyms": [
        {
          "_dis1": "100 0",
          "sense": "magazine",
          "word": "back issue"
        }
      ]
    },
    {
      "glosses": [
        "Anything considered old-fashioned."
      ],
      "id": "en-back_number-en-noun-b3jXUnI1",
      "links": [
        [
          "old-fashioned",
          "old-fashioned"
        ]
      ],
      "synonyms": [
        {
          "_dis1": "1 99",
          "sense": "something considered old-fashioned",
          "word": "has-been"
        }
      ]
    }
  ],
  "word": "back number"
}

{
  "categories": [
    "English countable nouns",
    "English entries with incorrect language header",
    "English entries with topic categories using raw markup",
    "English lemmas",
    "English multiword terms",
    "English nouns",
    "English terms with non-redundant non-automated sortkeys",
    "en:Periodicals"
  ],
  "forms": [
    {
      "form": "back numbers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "back number (plural back numbers)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English terms with quotations"
      ],
      "examples": [
        {
          "ref": "1941 December, “Back Numbers of \"The Railway Magazine\"”, in Railway Magazine, page 574",
          "text": "Because of war conditions and rigid paper control, it is now impossible for us to keep supplies of recent back numbers.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A back issue of a magazine, etc."
      ],
      "links": [
        [
          "back issue",
          "back issue"
        ],
        [
          "magazine",
          "magazine"
        ]
      ]
    },
    {
      "glosses": [
        "Anything considered old-fashioned."
      ],
      "links": [
        [
          "old-fashioned",
          "old-fashioned"
        ]
      ]
    }
  ],
  "synonyms": [
    {
      "sense": "magazine",
      "word": "back issue"
    },
    {
      "sense": "something considered old-fashioned",
      "word": "has-been"
    }
  ],
  "word": "back number"
}