"vanishing island" meaning in English

{
  "forms": [
    {
      "form": "vanishing islands",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "vanishing island (plural vanishing islands)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Landforms",
          "orig": "en:Landforms",
          "parents": [],
          "source": "w"
        }
      ],
      "coordinate_terms": [
        {
          "word": "tidal island#Noun"
        },
        {
          "word": "tied island#Noun"
        }
      ],
      "glosses": [
        "A permanent island which is exposed at low tide but is submersed at high tide."
      ],
      "hypernyms": [
        {
          "word": "island#Noun"
        },
        {
          "word": "isle#Noun"
        },
        {
          "word": "<"
        },
        {
          "word": "landform#Noun"
        }
      ],
      "id": "en-vanishing_island-en-noun-BQ~GONU8",
      "links": [
        [
          "low tide",
          "low tide"
        ],
        [
          "submersed",
          "submersed"
        ],
        [
          "high tide",
          "high tide"
        ]
      ]
    }
  ],
  "word": "vanishing island"
}

{
  "forms": [
    {
      "form": "vanishing islands",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "vanishing island (plural vanishing islands)",
      "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:Landforms"
      ],
      "coordinate_terms": [
        {
          "word": "tidal island#Noun"
        },
        {
          "word": "tied island#Noun"
        }
      ],
      "glosses": [
        "A permanent island which is exposed at low tide but is submersed at high tide."
      ],
      "hypernyms": [
        {
          "word": "island#Noun"
        },
        {
          "word": "isle#Noun"
        },
        {
          "word": "<"
        },
        {
          "word": "landform#Noun"
        }
      ],
      "links": [
        [
          "low tide",
          "low tide"
        ],
        [
          "submersed",
          "submersed"
        ],
        [
          "high tide",
          "high tide"
        ]
      ]
    }
  ],
  "word": "vanishing island"
}