bulge / bəlj/ • n. a rounded swelling or protuberance that distorts a flat surface. ∎  [in sing.] inf. a temporary unusual increase in number or size: a bulge in the birth rate.• v. [intr.] swell or protrude to an unnatural or incongruous extent: the veins in his neck bulged. ∎  be full of and distended with: a briefcase bulging with documents. ∎ DERIVATIVES: bulg·y adj.

bulge †wallet, pouch XIII; bottom of a ship's hull XVII; (f. the vb.) protuberance XVIII. — (O)F. bouge — L. bulga leathern sack, bag, of Gaulish orig.; the second sense is of obscure orig. (cf. BILGE).
Hence bulge vb. stave in the bottom of a ship; also intr. XVI; protrude XVII.