Source : Webster's Revised Unabridged Dictionary (1913)

Thomism \Tho"mism\, Thomaism \Tho"ma*ism\, n. (Eccl. Hist.)
   The doctrine of Thomas Aquinas, esp. with respect to
   predestination and grace.

Source : WordNet®

Thomism
     n : the comprehensive theological doctrine created by Saint
         Thomas Aquinas in the 13th century and still taught by
         the Dominicans