1. 边缘；周围；外围
If something is on the periphery of an area, place, or thing, it is on the edge of it.

2. （学科、兴趣的）边缘，次要部分
The periphery of a subject or area of interest is the part of it that is not considered to be as important or basic as the main part.

1. the outside boundary or surface of something

Synonym: fringeouter boundary