"lost river" meaning in English

{
  "forms": [
    {
      "form": "lost rivers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "lost river (plural lost rivers)",
      "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"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Hydrology",
          "orig": "en:Hydrology",
          "parents": [
            "Earth sciences",
            "Water",
            "Sciences",
            "Liquids",
            "All topics",
            "Matter",
            "Fundamental",
            "Chemistry",
            "Nature"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A surface stream which flows into an underground passageway."
      ],
      "id": "en-lost_river-en-noun-360qDboh",
      "links": [
        [
          "hydrology",
          "hydrology"
        ],
        [
          "surface",
          "surface"
        ],
        [
          "stream",
          "stream"
        ],
        [
          "flow",
          "flow"
        ],
        [
          "underground",
          "underground"
        ],
        [
          "passageway",
          "passageway"
        ]
      ],
      "raw_glosses": [
        "(hydrology) A surface stream which flows into an underground passageway."
      ],
      "topics": [
        "geography",
        "hydrology",
        "natural-sciences"
      ]
    }
  ],
  "word": "lost river"
}

{
  "forms": [
    {
      "form": "lost rivers",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "lost river (plural lost rivers)",
      "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",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Hydrology"
      ],
      "glosses": [
        "A surface stream which flows into an underground passageway."
      ],
      "links": [
        [
          "hydrology",
          "hydrology"
        ],
        [
          "surface",
          "surface"
        ],
        [
          "stream",
          "stream"
        ],
        [
          "flow",
          "flow"
        ],
        [
          "underground",
          "underground"
        ],
        [
          "passageway",
          "passageway"
        ]
      ],
      "raw_glosses": [
        "(hydrology) A surface stream which flows into an underground passageway."
      ],
      "topics": [
        "geography",
        "hydrology",
        "natural-sciences"
      ]
    }
  ],
  "word": "lost river"
}