noun
outline, border, verge, rim, beginning, end, terminal, confines, limit, limits, bounds, radius, terminus, landmark, march, extremity, fence, compass, side, purlieus, hem, frame, skirt, line of demarcation, termination, margin, line, barrier, frontier, outpost, perimeter, extent, circumference, horizon, periphery, fringe, pale, mark, borderland; see also edge 1.
Antonyms surface, interior, center.