(1):

(n.) A rolling, marshy, mossy plain of Northern Siberia.

(2):

(n.) One of the level or undulating treeless plains characteristic of northern arctic regions in both hemispheres. 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.