Optical disk and Videodisk

Optical disk noun - A disk coated with plastic that can store digital data as tiny pits etched in the surface; is read with a laser that scans the surface.

Videodisk and optical disk are semantically related. In some cases you can replace term "Videodisk" with "Optical disk", this terms are similar.

Videodisk noun - A digital recording (as of a movie) on an optical disk that can be played on a computer or a television set.

Optical disk and videodisk are semantically related. (American) You can use "Optical disk" instead a noun "Videodisk".