'hard disk' definitions:

Definition of 'hard disk'

From: WordNet
noun
A rigid magnetic disk mounted permanently in a drive unit [syn: hard disc, hard disk, fixed disk]

Definition of 'hard disk'

From: GCIDE
  • magnetic disc \magnetic disc\, magnetic disk \magnetic disk\n. A ditical memory device consisting of a flat disk covered with a magnetic coating on which information is stored; a hard disk, floppy disk, and diskette are typically magnetic disks.
  • Syn: disk, disc. [WordNet 1.5]