Dis"coid (?), a. [Gr. &?; quoit-shaped, &?; a round plate, quoit + &?; form, shape: cf. F. discoïde. 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.