DISC BULGING/BULGING DISC
When discs (See DISC) degenerate (See DISC DEGENERATION), they can flatten somewhat and the walls/annulus of the disc may bulge out. This is much like a cushion that begins as plump and, with time, becomes less plump and the sides of the cushion bulge outward.
Bulging discs can bulge all the way around and these are called diffusely bulging discs. If just one part of the disc bulges, it is called a focally bulging disc. Although bulging disc is the correct term, some people use the terms prolapsed disc/prolapsing disc or protruded/protruding disc.