Sclerosis is a medical condition in which a part inside your body becomes hard. see also multiple sclerosis. a disease that causes an organ or soft part of your body to become hard multiple sclerosis (sklerosis , from skleros ). progressive systemic sclerosis amyotrophic lateral sclerosis multiple sclerosis
A hardening within the nervous system, especially of the brain and spinal cord, resulting from degeneration of nervous elements such as the myelin sheath