Stenosis refers to the abnormal narrowing of a passage or opening in the body, which can occur in various anatomical structures, such as blood vessels, the spinal canal, or heart valves. This narrowing can lead to restricted blood flow, nerve compression, or other functional impairments, depending on its location. Common causes include congenital conditions, age-related changes, or diseases like Arthritis or atherosclerosis. Treatment often involves medication, physical therapy, or surgical intervention to alleviate symptoms and restore normal function.