Noun | 1. | ![]() frontal bone, os frontale, forehead - the large cranial bone forming the front part of the cranium: includes the upper part of the orbits excrescence, extrusion, gibbosity, gibbousness, hump, jut, bulge, protrusion, protuberance, swelling, bump, prominence - something that bulges out or is protuberant or projects from its surroundings; "the gun in his pocket made an obvious bulge"; "the hump of a camel"; "he stood on the rocky prominence"; "the occipital protuberance was well developed"; "the bony excrescence between its horns" |