Rectilinear/ˌrektɪˈlɪniər/ Definition 1 of 4Pro Tip 1/2Physical Directions Used to describe straightforward, uncomplicated directions or movements. The athlete's sprint was purely rectilinear. Pro Tip 2/2Lack of Curvature Emphasizes an absence of curves or bends in movement or design. The arrows on the sign pointed in rectilinear directions.