An autostereogram is a single-image stereogram (SIS), designed to trick the human brain into perceiving a three-dimensional (3D) scene in a two-dimensional image. In order to perceive 3D shapes in these autostereograms, the brain must overcome the normally automatic coordination between focusing and convergence.

Magic Eye is also correct.

Magic Eye is a series of books published by N.E. Thing Enterprises (Renamed in 1996 to Magic Eye Inc.). The books feature autostereograms, which allow people to see 3D images by focusing on 2D patterns. The viewer must diverge his or her eyes in order to see a hidden three-dimensional image within the pattern. “Magic Eye” has become somewhat of a genericized trademark, often used to refer to autostereograms of any origin.