\Dis"coid\, a. [Gr. ? quoit-shaped, ? a round plate,
quoit + ? form, shape: cf. F. disco["i]de. See {Disk}.]
Having the form of a disk, as those univalve shells which
have the whorls in one plane, so as to form a disk, as the
pearly nautilus.

{Discoid flower} (Bot.), a compound flower, consisting of
   tubular florets only, as a tansy, lacking the rays which
   are seen in the daisy and sunflower.

\Dis"coid\, n.
Anything having the form of a discus or disk; particularly, a
discoid shell.