Source : Webster's Revised Unabridged Dictionary (1913)

Periphery \Pe*riph"er*y\, n.; pl. {Peripheries}. [L. peripheria,
   Gr. ?; ? around + ? to bear, carry: cf. F. p['e]riph['e]rie.]
   1. The outside or superficial portions of a body; the
      surface.

   2. (Geom.) The circumference of a circle, ellipse, or other
      figure.

Source : WordNet®

periphery
     n : the outside boundary or surface of something [syn: {fringe},
          {outer boundary}]