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"
squeezing out by applying pressure;
"an unexpected extrusion of toothpaste from the bottom of the tube" "the expulsion of pus from the pimple"