compact disk

compact disc \com"pact disc`\, compact disk \com"pact disk`\(k[o^]m"p[a^]kt d[i^]sk`), n. a disk-shaped optical data storage medium approximately 4-3/4 in. in diameter, which stores binary data as microscopic nonreflective holes or pits in an otherwise reflective surface, and is recorded and played back by rotation in an electronic device containing a laser. It is often referred to by its abbreviation CD. It is a type of optical data storage medium. Compact disks are used for recordings of music as well as of data for computer applications.

laser disk \laser disk\ n. A digital data storage medium consisting of a thin disk onto which the data is impressed by a laser, in the form of a linear sequence of dots; same as optical disk. The data is subsequently read back by the use of a laser beam. See also compact disk.