from
The Collaborative International Dictionary of English v.0.48
Discoid \Dis"coid\, a. [Gr. ? quoit-shaped, ? a round plate,
quoit + e'i^dos 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.
[1913 Webster]
{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.
[1913 Webster]