hard disk

noun, Computers.
1.
magnetic disk (def 1).
Origin
1980-85
British Dictionary definitions for hard disks

hard disk

noun
1.
a disk of rigid magnetizable material that is used to store data for computers: it is permanently mounted in its disk drive and usually has a storage capacity of a few gigabytes
hard disks in Science
hard disk
  (härd)   
A rigid magnetic disk fixed within a disk drive and used for storing computer data. Hard disks hold more data than floppy disks, and data on a hard disk can be accessed faster than data on a floppy disk.