Source : Webster's Revised Unabridged Dictionary (1913)

Magnate \Mag"nate\, [F. magnat, L. (pl.) magnates, magnati, fr.
   magnus great. See {Master}.]
   1. A person of rank; a noble or grandee; a person of
      influence or distinction in any sphere.

Source : WordNet®

magnate
     n : a very wealthy or powerful businessman; "an oil baron" [syn:
          {baron}, {big businessman}, {business leader}, {king}, {mogul},
          {power}, {top executive}, {tycoon}]