Source : Webster's Revised Unabridged Dictionary (1913)

Hummock \Hum"mock\, n. [Prob. a dim. of hump. See {Hump}.]
   1. A rounded knoll or hillock; a rise of ground of no great
      extent, above a level surface.

   2. A ridge or pile of ice on an ice field.

   3. Timbered land. See {Hammock}. [Southern U.S.]

Source : WordNet®

hummock
     n : a small natural hill [syn: {knoll}, {mound}, {hillock}, {hammock}]