Lake Winnipegosis is a large (5,370 km2) lake in central North America, in Manitoba, Canada, some 300 km northwest of Winnipeg. It is Canada's eleventh-largest lake. An alternate spelling, once common but now rare, is Lake Winipigoos or simply 'Lake Winipigis'. The lake's name derives from that of Lake Winnipeg, with a diminutive suffix. Winnipeg means 'big muddy waters' and Winnipegosis means 'little muddy waters'. It appears as Winipgassish on the Fidler map of 1820, while modern spelling dates from as early as 1811.