Nuclear disk protrusion
A disk is a flat, round/oval structure, usually consisting of cartilage, found in joints as "shock absorbers". In the spine there is a disk between each vertebra. These disks may be pressed out between the vertebrae, e.g. when lifting something heavy with an abrupt movement. Such slipped disks may compress part of the spine and/or nerves branching from the spine causing severe (sciatic) pain in the legs.
GE Healthcare Glossary