The Collaborative International Dictionary of English v.0.48:

Sadducee \Sad"du*cee\, n. [L. Sadducaei, p., Gr. ?, Heb.
   Tsadd[=u]k[imac]m; -- so called from Ts[=a]d[=o]k, the
   founder of the sect.]
   One of a sect among the ancient Jews, who denied the
   resurrection, a future state, and the existence of angels. --
   Sad`du*ce"an, a.
   [1913 Webster] Sadduceeism

WordNet (r) 3.0 (2006):

Sadducee
    n 1: a member of an ancient Jewish sect around the time of
         Jesus; opposed to the Pharisees