"optical double" meaning in English

{
  "forms": [
    {
      "form": "optical doubles",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "optical double (plural optical doubles)",
      "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": "Entries with translation boxes",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
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          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with French translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Irish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Japanese translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Terms with Polish translations",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "langcode": "en",
          "name": "Stars",
          "orig": "en:Stars",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other."
      ],
      "id": "en-optical_double-en-noun-9PpPJ5rG",
      "links": [
        [
          "astronomy",
          "astronomy"
        ],
        [
          "star",
          "star"
        ]
      ],
      "raw_glosses": [
        "(astronomy) A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other."
      ],
      "related": [
        {
          "word": "visual binary"
        }
      ],
      "topics": [
        "astronomy",
        "natural-sciences"
      ],
      "translations": [
        {
          "code": "fr",
          "lang": "French",
          "lang_code": "fr",
          "sense": "star that appears as a double due to an optical illusion",
          "tags": [
            "feminine"
          ],
          "word": "étoile double optique"
        },
        {
          "code": "ga",
          "lang": "Irish",
          "lang_code": "ga",
          "sense": "star that appears as a double due to an optical illusion",
          "tags": [
            "feminine"
          ],
          "word": "réalta dhúbailte optúil"
        },
        {
          "code": "ja",
          "lang": "Japanese",
          "lang_code": "ja",
          "roman": "mikake no nijūsei",
          "sense": "star that appears as a double due to an optical illusion",
          "word": "見かけの二重星"
        },
        {
          "code": "pl",
          "lang": "Polish",
          "lang_code": "pl",
          "sense": "star that appears as a double due to an optical illusion",
          "tags": [
            "feminine"
          ],
          "word": "optyczna gwiazda podwójna"
        }
      ]
    }
  ],
  "word": "optical double"
}

{
  "forms": [
    {
      "form": "optical doubles",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "optical double (plural optical doubles)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "visual binary"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Entries with translation boxes",
        "Pages with 1 entry",
        "Pages with entries",
        "Terms with French translations",
        "Terms with Irish translations",
        "Terms with Japanese translations",
        "Terms with Polish translations",
        "en:Stars"
      ],
      "glosses": [
        "A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other."
      ],
      "links": [
        [
          "astronomy",
          "astronomy"
        ],
        [
          "star",
          "star"
        ]
      ],
      "raw_glosses": [
        "(astronomy) A star that appears as a double due to an optical illusion; in reality, the stars may be far apart from each other."
      ],
      "topics": [
        "astronomy",
        "natural-sciences"
      ]
    }
  ],
  "translations": [
    {
      "code": "fr",
      "lang": "French",
      "lang_code": "fr",
      "sense": "star that appears as a double due to an optical illusion",
      "tags": [
        "feminine"
      ],
      "word": "étoile double optique"
    },
    {
      "code": "ga",
      "lang": "Irish",
      "lang_code": "ga",
      "sense": "star that appears as a double due to an optical illusion",
      "tags": [
        "feminine"
      ],
      "word": "réalta dhúbailte optúil"
    },
    {
      "code": "ja",
      "lang": "Japanese",
      "lang_code": "ja",
      "roman": "mikake no nijūsei",
      "sense": "star that appears as a double due to an optical illusion",
      "word": "見かけの二重星"
    },
    {
      "code": "pl",
      "lang": "Polish",
      "lang_code": "pl",
      "sense": "star that appears as a double due to an optical illusion",
      "tags": [
        "feminine"
      ],
      "word": "optyczna gwiazda podwójna"
    }
  ],
  "word": "optical double"
}