גַב gab (H1354)

the back (as rounded); by analogy, the top or rim, a boss, a vault, arch of eye, bulwarks, etc.

1) convex surface, back 1a) back (of man) 1b) mound (for illicit worship) 1c) boss (convex projection of shield) 1d) bulwarks, breastworks (of arguments-fig.) 1e) brow, eyebrow 1f) rim (of wheel)

from an unused root meaning to hollow or curve; (compare גֵּו (H1460) and גּוּף (H1479))