rupture of the intervertebral disk cartilage, which allows the contents to protrude through it, putting pressure on the spinal nerve roots; also called slipped disk, ruptured disk, herniated intervertebral disk, or herniated nucleus pulposus (HNP).upture of the intervertebral disk cartilage, which allows the contents to protrude through it, putting pressure on the spinal nerve roots; also called slipped disk, ruptured disk, herniated intervertebral disk, or herniated nucleus pulposus (HNP).