Having boundaries; enclosed: a closed corridor between the two buildings. Blocked or barred to passage or entry: a closed port. Explicitly limited; restricted: closed membership. Self-contained or self-sufficient: a closed relationship. Barred to the public; conducted in secrecy: a closed session of the judiciary committee. Mathematics Of or relating to a curve, such as a circle, having no endpoints. Mathematics Of or relating to a surface having no boundary curves. Mathematics Of or relating to an interval containing both its endpoints. Mathematics Characterized by or possessing the property by which an operation acting on an element in a set produces an element within the set. Computer Science Of or relating to a file that cannot be accessed. Electricity Allowing electricity to flow or pass: a closed switch. Linguistics Ending in a consonant: a closed syllable. Sports Having the forward foot closer to the intended point of impact with the ball than the rear foot: a closed batting stance. Sports Held or swung with the top or outer edge of the striking face pointing slightly closer to the objective than the lower or inner edge: The club face was closed when it hit the ball, causing a hook. Physics Relating to a model of the universe in which the mass of the universe is sufficient to halt its expansion, and in which its curvature resembles that of a sphere, such that an object moving in a straight line would eventually return to its starting point.