the external boundary of any surface or area.

the external surface of a body.

the edge or outskirts, as of a city or urban area.

the relatively minor, irrelevant, or superficial aspects of the subject in question

The preliminary research did not, of course, take me beyond the periphery of my problem.

Anatomy . the area in which nerves end.

noun

center

noun

ambit , border , boundary , brim , brink , circuit , circumference , compass , covering , edge , fringe , hem , margin , outside , perimeter , rim , skirt , verge , borderline , edging , edges , environs , limit , outskirts , surface