a film that has a three-dimensional, stereoscopic form or appearance, giving the life-like illusion of depth; often achieved by viewers donning special red/blue (or green) or polarized lens glasses; when 3-D images are made interactive so that users feel involved with the scene, the experience is called virtual reality; 3-D experienced a heyday in the early 1950s; aka 3D, three-D, Stereoscopic 3D, Natural Vision 3D, or three-dimensional