"land under" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "de",
        "3": "Land unter"
      },
      "expansion": "Calque of German Land unter",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of German Land unter.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "land under (uncountable)",
      "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": [
        "Complete flooding of a North Sea Hallig during a storm tide."
      ],
      "id": "en-land_under-en-noun-413pNIDR",
      "links": [
        [
          "flooding",
          "flooding"
        ],
        [
          "North Sea",
          "North Sea"
        ],
        [
          "Hallig",
          "Hallig"
        ],
        [
          "storm tide",
          "storm tide"
        ]
      ],
      "tags": [
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "rhymes": "-ʌndə(ɹ)"
    }
  ],
  "word": "land under"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "de",
        "3": "Land unter"
      },
      "expansion": "Calque of German Land unter",
      "name": "calque"
    }
  ],
  "etymology_text": "Calque of German Land unter.",
  "head_templates": [
    {
      "args": {
        "1": "-"
      },
      "expansion": "land under (uncountable)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms calqued from German",
        "English terms derived from German",
        "English uncountable nouns",
        "Rhymes:English/ʌndə(ɹ)",
        "Rhymes:English/ʌndə(ɹ)/3 syllables"
      ],
      "glosses": [
        "Complete flooding of a North Sea Hallig during a storm tide."
      ],
      "links": [
        [
          "flooding",
          "flooding"
        ],
        [
          "North Sea",
          "North Sea"
        ],
        [
          "Hallig",
          "Hallig"
        ],
        [
          "storm tide",
          "storm tide"
        ]
      ],
      "tags": [
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "rhymes": "-ʌndə(ɹ)"
    }
  ],
  "word": "land under"
}