arsenous oxide(n = noun.substance) arsenic, arsenic trioxide, arsenous anhydride, ratsbane, white arsenic - a white powdered poisonous trioxide of arsenic; used in manufacturing glass and as a pesticide (rat poison) and weed killer;
is a kind of trioxide

aluminium oxide, aluminum oxide, arsenous anhydride, barium oxide, calcium oxide, copper oxide, deuterium oxide, ferric oxide, hydrated aluminium oxide, hydrated aluminum oxide, hydrated oxide, iron oxide, magnesium oxide, nitric oxide, nitrogen oxide, nitrous oxide, oxide, silicon oxide, sulfur oxide, sulphur oxide, titanic oxide, titanium oxide, zinc oxide, zirconium oxide