"liquid mirror" meaning in English

{
  "forms": [
    {
      "form": "liquid mirrors",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
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      "args": {},
      "expansion": "liquid mirror (plural liquid mirrors)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
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      "categories": [
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          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
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          "source": "w"
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          "parents": [],
          "source": "w"
        }
      ],
      "derived": [
        {
          "word": "liquid mirror telescope"
        }
      ],
      "glosses": [
        "A mirror made from a layer of reflective liquid."
      ],
      "id": "en-liquid_mirror-en-noun-nQdRpsOu",
      "links": [
        [
          "reflective",
          "reflective"
        ]
      ],
      "wikipedia": [
        "liquid mirror"
      ]
    }
  ],
  "word": "liquid mirror"
}

{
  "derived": [
    {
      "word": "liquid mirror telescope"
    }
  ],
  "forms": [
    {
      "form": "liquid mirrors",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "liquid mirror (plural liquid mirrors)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
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        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
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      ],
      "glosses": [
        "A mirror made from a layer of reflective liquid."
      ],
      "links": [
        [
          "reflective",
          "reflective"
        ]
      ],
      "wikipedia": [
        "liquid mirror"
      ]
    }
  ],
  "word": "liquid mirror"
}