Ogee : A reverse curve, shaped like an elongated letter S. The downstream faces of overflow dams are often made to this shape. (From the French word Ogive)
National Weather Service NWS Forecast Office, National Oceanic and Atmospheric Administration NOAA, SH Manual, Glossary of Hydrologic Terms, Washington, DC, USA 2015. http://www.nws.noaa.gov/om/hod/SHManual/SHMan014_g lossary.htm, (HydroI - Amer) {889}