"book packet" meaning in English

{
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "book packet",
      "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"
        }
      ],
      "glosses": [
        "A packet or parcel containing printed matter, especially one which may be sent through the mail at a reduced rate."
      ],
      "id": "en-book_packet-en-noun-sE2yR-3V",
      "links": [
        [
          "printed matter",
          "printed matter"
        ],
        [
          "mail",
          "mail"
        ],
        [
          "reduced",
          "reduced"
        ],
        [
          "rate",
          "rate"
        ]
      ],
      "raw_glosses": [
        "(dated, obsolete) A packet or parcel containing printed matter, especially one which may be sent through the mail at a reduced rate."
      ],
      "tags": [
        "dated",
        "obsolete"
      ]
    }
  ],
  "word": "book packet"
}

{
  "head_templates": [
    {
      "args": {
        "1": "?"
      },
      "expansion": "book packet",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English dated terms",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English nouns with unknown or uncertain plurals",
        "English terms with obsolete senses"
      ],
      "glosses": [
        "A packet or parcel containing printed matter, especially one which may be sent through the mail at a reduced rate."
      ],
      "links": [
        [
          "printed matter",
          "printed matter"
        ],
        [
          "mail",
          "mail"
        ],
        [
          "reduced",
          "reduced"
        ],
        [
          "rate",
          "rate"
        ]
      ],
      "raw_glosses": [
        "(dated, obsolete) A packet or parcel containing printed matter, especially one which may be sent through the mail at a reduced rate."
      ],
      "tags": [
        "dated",
        "obsolete"
      ]
    }
  ],
  "word": "book packet"
}