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 disk 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.
hard disk in Technology
storage (In contrast to floppy disk) A magnetic disk data storage device where the disks are rigid and fixed to a central axle. They are usually packaged with associated read/write heads and electronics. Most hard disks are permanently connected to the drive (fixed disks) though there are also removable hard disks. See magnetic disk. (2007-06-14)