View-Master is a stereoscopic toy where a circular cardboard disk with small photographs is inserted into it and viewed through special lenses. There are different synonyms for View-Master, such as 3D viewer, stereoscope, stereopticon, magic lantern, and optical viewer. A 3D viewer is a device that displays images with depth perception. A stereoscope is an optical instrument for displaying images with depth perception. A stereopticon is a device that combines two images to create a single 3D image. A magic lantern is a device that projects images onto a screen, while an optical viewer is a device that provides magnified images. All of these synonyms refer to a device that allows you to see images in a unique and often immersive way.