FLOPPY DISK

Floppy disk: A soft magnetic disk. It is called floppy because it flops if you wave it (at least, the 5¼-inch variety does). Unlike most hard disk, floppy disk (often called floppies or diskettes) are portable, because you can remove them from a disk drive.

Disk drives for floppy disks are called floppy drives. Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive. And most importantly, they are portable.