Source : Webster's Revised Unabridged Dictionary (1913)

Stela \Ste"la\, n.; pl. {Stel[ae]}. [L., from Gr. ? a post, an
   upright stone.] (Gr. Antiq.)
   A small column or pillar, used as a monument, milestone, etc.

Source : WordNet®

stele
     n 1: the usually cylindrical central vascular portion of the axis
          of a vascular plant
     2: an ancient upright stone slab bearing markings [syn: {stela}]
     [also: {stelae} (pl)]

stelae
     See {stele}