anorthoscope

Century Dictionary and Cyclopedia

1. n. An instrument for producing a peculiar kind of optical illusion by means of two disks rotating rapidly one behind the other. The posterior disk is transparent, and has certain distorted figures painted upon it; the anterior is opaque, but pierced with a number of narrow slits, through which the figures on the posterior disk are viewed. The effect depends on the persistence of impressions on the retina, the instrument being in principle the same as the zoëtrope.

Wiktionary

1. n. An optical device (often a toy) used to produce a form of anamorphosis or to view distorted figures

GNU Webster's 1913

1. n. (Physics) An optical toy for producing amusing figures or pictures by means of two revolving disks, on one of which distorted figures are painted.