"acoustic mirror" meaning in English

{
  "forms": [
    {
      "form": "acoustic mirrors",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "acoustic mirror (plural acoustic mirrors)",
      "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"
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          "source": "w"
        },
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          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Sound",
          "orig": "en:Sound",
          "parents": [
            "Energy",
            "Nature",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A passive device for reflecting and often focusing sound waves, chiefly used to provide early warning of incoming aircraft (by detecting the sound of their engines)."
      ],
      "id": "en-acoustic_mirror-en-noun-ZF0hxnJF",
      "links": [
        [
          "passive",
          "passive"
        ],
        [
          "focus",
          "focus"
        ],
        [
          "sound",
          "sound"
        ]
      ],
      "related": [
        {
          "word": "war tuba"
        },
        {
          "word": "parabolic microphone"
        }
      ],
      "synonyms": [
        {
          "word": "sound mirror"
        }
      ]
    }
  ],
  "word": "acoustic mirror"
}

{
  "forms": [
    {
      "form": "acoustic mirrors",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "acoustic mirror (plural acoustic mirrors)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "war tuba"
    },
    {
      "word": "parabolic microphone"
    }
  ],
  "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:Sound"
      ],
      "glosses": [
        "A passive device for reflecting and often focusing sound waves, chiefly used to provide early warning of incoming aircraft (by detecting the sound of their engines)."
      ],
      "links": [
        [
          "passive",
          "passive"
        ],
        [
          "focus",
          "focus"
        ],
        [
          "sound",
          "sound"
        ]
      ]
    }
  ],
  "synonyms": [
    {
      "word": "sound mirror"
    }
  ],
  "word": "acoustic mirror"
}