Septum: A dividing wall or enclosure. For example, the septum of the nose is the thin cartilage that divides the left and right chambers of the nose from each other. From Healthy Resources 10 Rheumatoid Arthritis Symptoms How IL Inhibitors Work to Treat PsoriasisModerate to Severe UC: Targeted Solutions Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew