n. vast treeless plain near the Arctic Circle where the subsoil is permanently frozen "There are cold, rockly islands and stretches of tundra where no trees grow."
n. a small, short-tailed, thickset rodent "On land, a polar bear might catch a tiny lemming."
n. an insulating layer of fat under the skin of whales and other large marine mammals "Like a snug blanket, this blubber keeps in the heat of the bear's body."