The Collaborative International Dictionary of English v.0.48:

Trappist \Trap"pist\, n. [F. trappiste.] (R. C. Ch.)
   A monk belonging to a branch of the Cistercian Order, which
   was established by Armand de Ranc['e] in 1660 at the
   monastery of La Trappe in Normandy. Extreme austerity
   characterizes their discipline. They were introduced
   permanently into the United States in 1848, and have
   monasteries in Iowa and Kentucky.
   [1913 Webster]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Trappist
    n 1: member of an order of monks noted for austerity and a vow
         of silence [syn: Trappist, Cistercian]