Source : Webster's Revised Unabridged Dictionary (1913)

Suppressor \Sup*press"or\, n. [L., hider.]
   One who suppresses.

Source : WordNet®

suppressor
     n 1: someone who suppresses; "dictators are suppressors of free
          speech" [syn: {suppresser}]
     2: a gene that suppresses the phenotypic expression of another
        gene (especially of a mutant gene) [syn: {suppresser}, {suppressor
        gene}, {suppresser gene}]
     3: an electrical device for suppressing unwanted currents [syn:
         {suppresser}]