The Collaborative International Dictionary of English v.0.48:

Cyathiform \Cy*ath"i*form\ (s?-?th"?-f?rm), a. [L. cyathus a cup
   (Gr, ky`aqos) -form:cf. F. cyathiforme.]
   In the form of a cup, a little widened at the top.
   [1913 Webster]