Source : Webster's Revised Unabridged Dictionary (1913)

Necessitarianism \Ne*ces`si*ta"ri*an*ism\, n.
   The doctrine of philosophical necessity; the doctrine that
   results follow by invariable sequence from causes, and esp.
   that the will is not free, but that human actions and choices
   result inevitably from motives; deteminism. --M. Arnold.