Penrose stairs

Etymology
After a drawing by Lionel Penrose and Roger Penrose.

Noun

 * 1) An impossible loop of endlessly ascending and descending stairs, or an optical illusion appearing to depict such a loop.

Synonyms

 * impossible staircase

Translations

 * Finnish: Penrosen portaat
 * German: unmögliche Treppe
 * Swedish: Penroses trappa