Disk \Disk\, n. [L. discus, Gr. ?. See Dish.]
[Written also
disc.]
1. A discus; a quoit.
Some whirl the disk, and some the javelin dart.
--Pope.
2. A flat, circular plate; as, a disk of metal or paper.
3. (Astron.) The circular figure of a celestial body, as seen
projected of the heavens.
4. (Biol.) A circular structure either in plants or animals;
as, a blood disk; germinal disk, etc.
5. (Bot.)
(a) The whole surface of a leaf.
(b) The central part of a radiate compound flower, as in
sunflower.
(c) A part of the receptacle enlarged or expanded under,
or around, or even on top of, the pistil.
6. (Zo["o]l.)
(a) The anterior surface or oral area of c[oe]lenterate
animals, as of sea anemones.
(b) The lower side of the body of some invertebrates,
especially when used for locomotion, when it is often
called a creeping disk.
(c) In owls, the space around the eyes.
Disk engine, a form of rotary steam engine.
Disk shell (Zo["o]l.), any species of Discina.
Source: Webster's Revised Unabridged Dictionary (1913)
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