The Sauer is a tributary river to the Moselle, flowing through Belgium, Luxembourg and Germany. Sauer is a German surname, see Sauer (surname). The word sauer means sour, acidic. Sauer may also refer to: Sauer (Altenau), a river of North Rhine-Westphalia, Germany Sauer (Rhine), a river in France and Germany Sauer & Sohn (founded 1751), a German firearms manufacturer Sauer Castle, an architecturally significant house in Kansas City, Kansas (US) Sauer Commission (created 1947), a South African study of segregation policies C. F. Sauer Company (founded 1887), a cooking products manufacturer SIG Sauer, US arm of Swiss manufacturing firm Swiss Arms AG Paul Sauer Bridge, a highway bridge in South Africa Cube 2: Sauerbraten, a 2004 popular on-line game Sauer Van, a gas van used in the Sajmište concentration camp See also Saur (disambiguation)