"joint line" meaning in English

{
  "forms": [
    {
      "form": "joint lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "joint line (plural joint lines)",
      "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": "topical",
          "langcode": "en",
          "name": "Rail transportation",
          "orig": "en:Rail transportation",
          "parents": [
            "Transport",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1959 April, “Motive Power Miscellany: London Midland Region”, in Trains Illustrated, page 221",
          "text": "The engine was No. 60920, which was seen passing southbound through Preston and then at about 1.0 p.m. heading its train over the former joint line from Warrington via Helsby to the Chester district; [...]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A railway that is or was owned and operated by more than one company."
      ],
      "id": "en-joint_line-en-noun-ZVj5JcIv",
      "links": [
        [
          "rail transport",
          "rail transport"
        ]
      ],
      "raw_glosses": [
        "(rail transport) A railway that is or was owned and operated by more than one company."
      ],
      "topics": [
        "rail-transport",
        "railways",
        "transport"
      ]
    }
  ],
  "word": "joint line"
}

{
  "forms": [
    {
      "form": "joint lines",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "joint line (plural joint lines)",
      "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",
        "en:Rail transportation"
      ],
      "examples": [
        {
          "ref": "1959 April, “Motive Power Miscellany: London Midland Region”, in Trains Illustrated, page 221",
          "text": "The engine was No. 60920, which was seen passing southbound through Preston and then at about 1.0 p.m. heading its train over the former joint line from Warrington via Helsby to the Chester district; [...]",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A railway that is or was owned and operated by more than one company."
      ],
      "links": [
        [
          "rail transport",
          "rail transport"
        ]
      ],
      "raw_glosses": [
        "(rail transport) A railway that is or was owned and operated by more than one company."
      ],
      "topics": [
        "rail-transport",
        "railways",
        "transport"
      ]
    }
  ],
  "word": "joint line"
}