Stenosis is an abnormal narrowing of a canal, valve or passage in the body. Stenosis in the spine, for example, is characterized by narrowing of the spinal canal, which can in turn put pressure on the spinal cord and nerves and cause pain.
Spinal stenosis can cause numbness, weakness or tingling in the legs, feet, arm or hands, and/or, in severe cases, problems with bladder and bowel function. Symptoms typically start gradually and worsen over time.
Resource: NIH