dis·coid 
(dĭskoid′) also dis·coi·dal (dĭ-skoidl)
(dĭskoid′) also dis·coi·dal (dĭ-skoidl)adj.
1. Having a flat, circular form; disk-shaped.
2. Related to or having a disk.
3. Having disk flowers only. Used of a composite flower head.
discoid′ n.