Periphery Definitions

pe·riph·er·y (pə-rĭf'ə-rē) n., pl. -ies.
A line that forms the boundary of an area; a perimeter.
The surface of a solid.

The outermost part or region within a precise boundary.
A zone constituting an imprecise boundary.
[Middle English periferie, from Medieval Latin periferia, from Late Latin peripherīa, from Greek periphereia, from peripherēs, carrying around : peri-, peri- + pherein, to carry.]

periphery
noun
A line around a closed figure or area: ambit, circuit, circumference, compass, perimeter. See edge/center.

A fairly narrow line or space forming a boundary: border, borderline, brim, brink, edge, edging, fringe, margin, rim, verge. Chiefly Military perimeter. See edge/center.

periphery n
Definition: outskirts, outer edgeAntonyms: center, heart, middle
Peripheral vision is that part of visual perception that occurs in the periphery, i.e., near the edges, of the field of view.

The Periphery includes nations that are not core countries - capitalist or industrialized nations.

The 10 peripheries of Greece are subnational subdivisions of that country, equivalent to regions.

In BattleTech game, the Periphery is the region filled with less developed space colonies, most distant from Earth.

From Answers.com and Wikipedia