A computer disk enclosed in a protective case (hard disk) or jacket (floppy disk) and coated with a magnetic material that enables data to be stored in the form of changes in magnetic polarity (with one polarity representing a binary 1 and the other a 0) on many small sections (magnetic domains) of the disk surface. Magnetic disks should be protected from exposure to sources of magnetism, which can damage or destroy the information they hold. See also disk, floppy disk, hard disk. Compare compact disc, magneto-optic disc.
(Computer science) A memory device consisting of a flat disk covered with a magnetic coating on which information is stored; SYN. magnetic disc, disk, disc.