The Collaborative International Dictionary of English v.0.48:

Juglans \Jug"lans\, n. [L., walnut.] (Bot.)
   A genus of valuable trees, including the true walnut of
   Europe, and the America black walnut, and butternut.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Juglans
    n 1: type genus of the Juglandaceae [syn: Juglans, genus
         Juglans]