Disc

or DISK, (disk.) [Gr. dis kos.] (Astron.) The body and face of the sun or moon, or of a planet, as it appears to us on the earth; or the body and face of the earth, as it would appear to a spectator at the moon. The fixed stars are destitute of any apparent disc, even when viewed by the best telescopes.-(Opt.) The magnitude of the lens of a telescope, or the width of its aperture. (Bot.) The part inside the ray of a radiated compound flower, such as is seen in the marigold or daisy. [s. 290]