The tundra is a vast treeless plain near the Arctic Circle where the subsoil is permanently frozen. Despite the stark cold, many animals thrive on the tundra, including insects, migrating birds, and foxes.
A tundra is a great description of any stark icy cold place — say, the walk to class on a college campus during February — but it is an actual geographic location, near the Arctic circle in North America, Russia, and Scandinavia. Smaller tundras can exist near the South Pole but it's often too cold there. The word comes from the Finnish tunturria which means "barren land." Santa's reindeer live on the tundra and go by the name of caribou in North America. Of course, none of them can fly.