Compact disk and Optical disc

Compact disk noun - A digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser.

Optical disc and compact disk are semantically related In some cases you can use "Optical disc" instead a noun phrase "Compact disk".

Optical disc 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.

Compact disk and optical disc are semantically related in magnetic medium topic. You can use "Compact disk" instead a noun phrase "Optical disc".