Source : Webster's Revised Unabridged Dictionary (1913)

Potentiate \Po*ten"ti*ate\, v. t. [imp. & p. p. {Potentiated};
   p. pr. & vb. n. {Potentiating}.]
   To render active or potent. --Coleridge.

Source : WordNet®

potentiate
     v : increase the effect of or act synergistically with (a drug
         or a physiological or biochemical phenomenon);
         "potentiate the drug"