Real Dictionary

reindeer
countable noun: A reindeer is a deer with large horns called antlers that lives in northern areas of Europe, Asia, and America.

reindeer in American English
any of a genus (Rangifer) of large deer, including the caribou, with branching antlers in both sexes, found in northern regions: it is domesticated as a beast of burden and as a source of milk, meat, and leather
noun: any of several large deer of the genus Rangifer, of northern and arctic regions of Europe, Asia, and North America, both male and female of which have antlers

reindeer in British English
noun: a large deer, Rangifer tarandus, having large branched antlers in the male and female and inhabiting the arctic regions of Greenland, Europe, and Asia. It also occurs in North America, where it is known as a caribou