"Penrose triangle" meaning in English

{
  "etymology_text": "After Roger Penrose (1931-), English mathematician, who popularised it in the 1950s.",
  "forms": [
    {
      "form": "Penrose triangles",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Penrose triangle (plural Penrose triangles)",
      "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": "Pages with 1 entry",
          "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 depicting an impossible solid object made of three straight beams of square cross section which meet pairwise at right angles at the vertices of the triangle they form."
      ],
      "id": "en-Penrose_triangle-en-noun-PK9~Ov3~",
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "beam",
          "beam"
        ],
        [
          "cross section",
          "cross section"
        ],
        [
          "pairwise",
          "pairwise"
        ],
        [
          "right angle",
          "right angle"
        ],
        [
          "vertices",
          "vertex"
        ],
        [
          "triangle",
          "triangle"
        ]
      ],
      "related": [
        {
          "word": "Necker cube"
        }
      ],
      "wikipedia": [
        "Penrose triangle"
      ]
    }
  ],
  "word": "Penrose triangle"
}

{
  "etymology_text": "After Roger Penrose (1931-), English mathematician, who popularised it in the 1950s.",
  "forms": [
    {
      "form": "Penrose triangles",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "Penrose triangle (plural Penrose triangles)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "Necker cube"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English eponyms",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries",
        "en:Optical illusions"
      ],
      "glosses": [
        "An optical illusion depicting an impossible solid object made of three straight beams of square cross section which meet pairwise at right angles at the vertices of the triangle they form."
      ],
      "links": [
        [
          "optical illusion",
          "optical illusion"
        ],
        [
          "beam",
          "beam"
        ],
        [
          "cross section",
          "cross section"
        ],
        [
          "pairwise",
          "pairwise"
        ],
        [
          "right angle",
          "right angle"
        ],
        [
          "vertices",
          "vertex"
        ],
        [
          "triangle",
          "triangle"
        ]
      ],
      "wikipedia": [
        "Penrose triangle"
      ]
    }
  ],
  "word": "Penrose triangle"
}