Source : Webster's Revised Unabridged Dictionary (1913)

Occasionalism \Oc*ca"sion*al*ism\, n. (Metaph.)
   The system of occasional causes; -- a name given to certain
   theories of the Cartesian school of philosophers, as to the
   intervention of the First Cause, by which they account for
   the apparent reciprocal action of the soul and the body.