"Delboeuf illusion" meaning in English

{
  "etymology_text": "Discovered in 1865 by the Belgian scientist Joseph Remi Leopold Delboeuf (1831–1896).",
  "forms": [
    {
      "form": "Delboeuf illusions",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Delboeuf illusion (plural Delboeuf illusions)",
      "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"
        },
        {
          "kind": "other",
          "name": "English entries with language name categories using raw markup",
          "parents": [
            "Entries with language name categories using raw markup",
            "Entry maintenance"
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          "source": "w"
        },
        {
          "kind": "other",
          "name": "English terms with non-redundant non-automated sortkeys",
          "parents": [
            "Terms with non-redundant non-automated sortkeys",
            "Entry maintenance"
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          "source": "w"
        },
        {
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          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Optical illusions",
          "orig": "en:Optical illusions",
          "parents": [
            "Vision",
            "Senses",
            "Perception",
            "Body",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "An optical illusion of relative size perception, usually illustrated by two discs of identical size, one of which is surrounded by a ring."
      ],
      "id": "en-Delboeuf_illusion-en-noun-owewYeTk",
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "relative",
          "relative"
        ],
        [
          "size",
          "size"
        ],
        [
          "perception",
          "perception"
        ],
        [
          "ring",
          "ring"
        ]
      ]
    }
  ],
  "word": "Delboeuf illusion"
}

{
  "etymology_text": "Discovered in 1865 by the Belgian scientist Joseph Remi Leopold Delboeuf (1831–1896).",
  "forms": [
    {
      "form": "Delboeuf illusions",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Delboeuf illusion (plural Delboeuf illusions)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English entries with language name categories using raw markup",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with non-redundant non-automated sortkeys",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Optical illusions"
      ],
      "glosses": [
        "An optical illusion of relative size perception, usually illustrated by two discs of identical size, one of which is surrounded by a ring."
      ],
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "relative",
          "relative"
        ],
        [
          "size",
          "size"
        ],
        [
          "perception",
          "perception"
        ],
        [
          "ring",
          "ring"
        ]
      ]
    }
  ],
  "word": "Delboeuf illusion"
}