reindeer, Any species of Arctic deer in the genus Rangifer (family Cervidae), especially Old World species, some of which are domesticated. New World species are usually called caribou. The reindeer herded by the Sami (Lapps) are used as draft and pack animals and as a source of meat and milk; their skins are used for tents, boots, and other clothing. In Siberia they are used as pack animals and as mounts.