Source : Webster's Revised Unabridged Dictionary (1913)

Herma \Her"ma\, n.; pl. {Herm[ae]}. [L.]
   See {Hermes},

   2.

Source : WordNet®

herm
     n : a statue consisting of a squared stone pillar with a carved
         head (usually a bearded Hermes) on top; used in ancient
         Greece as a boundary marker or signpost
     [also: {hermae} (pl)]

hermae
     See {herm}