(computing) a virtual disk, implemented in software, that stores its contents in RAM.

The hyperbolic plane, viewed as a disk so that Euclidean circles and lines Euclidean-perpendicular to the disk's surface are hyperbolic lines.

(computing, dated) An 8-inch or 5.25-inch floppy diskette having storage capacity on both sides, and needing to be removed from the drive, flipped over and reinserted in order to access the other side.

A circular disk used to measure water transparency (and thus turbidity)

(computing, dated) A hard disk.

Alternative spelling of optical disc

Alternative form of parking disc

Alternative form of Nipkow disk

(mathematics) A set of points on a plane whose distance from a given point is less than or equal to one.

(computer hardware) A floppy drive; a disk drive for floppy disks.