Compact disc and Optical disc

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

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 disc and optical disc are semantically related. Sometimes you can replace phrase "Compact disc" with "Optical disc", this phrases are similar.