‖n. [ Russ. ] One of the level or undulating treeless plains characteristic of northern arctic regions in both hemispheres; the term is most commony associated with the arctic plains of Siberia. The tundras mark the limit of arborescent vegetation; they consist of black mucky soil with a permanently frozen subsoil, but support a dense growth of mosses and lichens, and dwarf herbs and shrubs, often showy-flowered. [ Webster 1913 Suppl. ]