The Collaborative International Dictionary of English v.0.48:

Periphery \Pe*riph"er*y\, n.; pl. Peripheries. [L. peripheria,
   Gr. perife`reia; peri` around + fe`rein to bear, carry: cf.
   F. p['e]riph['e]rie.]
   1. The outside or superficial portions of a body; the
      surface.
      [1913 Webster]

   2. (Geom.) The circumference of a circle, ellipse, or other
      figure.
      [1913 Webster]