The Collaborative International Dictionary of English v.0.48:

Cycas \Cy"cas\ (s?"k?s), n. [Of uncertain origin. Linn[ae]us
   derives it from one of the "obscure Greek words."] (Bot.)
   A genus of trees, intermediate in character between the palms
   and the pines. The pith of the trunk of some species
   furnishes a valuable kind of sago.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Cycas
    n 1: type genus of Cycadaceae: genus of widely distributed Old
         World evergreen tropical trees having pinnate leaves and
         columnar stems covered with persistent bases of old leaves
         [syn: Cycas, genus Cycas]