dongle-disk /don'gl disk/ n. A special floppy disk that
is required in order to perform some task. Some contain special
coding that allows an application to identify it uniquely, others
*are* special code that does something that normally-resident
programs don't or can't. (For example, AT&T's "Unix PC" would
only come up in {root mode} with a special boot disk.) Also
called a `key disk'. See {dongle}.