magnetic disk

noun, Computers.
1.
Also called disk, hard disk. a rigid disk coated with magnetic material, on which data and programs can be stored.
2.
floppy disk.
British Dictionary definitions for magnetic disks

magnetic disk

noun
1.
(computing) another name for disk (sense 2)
magnetic disks in Science
magnetic disk  
A memory device, such as a floppy disk or a hard disk, that is covered with a magnetic coating. Digital information is stored on magnetic disks in the form of microscopically small, magnetized needles, each of which encodes a single bit of information by being polarized in one direction (representing 1) or the other (representing 0).