Source : Webster's Revised Unabridged Dictionary (1913)

Cyathophylloid \Cy`a*tho*phyl"loid\, n. (Paleon.)
   A fossil coral of the family {Cyathophyllid[ae]}; sometimes
   extended to fossil corals of other related families belonging
   to the group Rugosa; -- also called {cup corals}. Thay are
   found in paleozoic rocks.