Definition of "reindeer"

Here is a prodigious number of wild beaſts, as ſtags, bears, wolves, foxes of various colours, martens, hares, glittens, beavers, otters, elk, and rein deer: the latter is leſs than a stag.

1768, D[aniel] Fenning, “LAPLAND”, in The Royal English Dictionary; or, A Treasury of the English Language, 3rd improved edition, London: Printed for R. Baldwin, Hawes and Co., T. Caslon, S. Crowder, J. Johnson, Wilson and Fell, Robinson and Roberts, and B. Collins

Reindeer are well suited to the taiga’s frigid winters. They can maintain a thermogradient between body core and the environment of up to 100 degrees, in part because of insulation provided by their fur, and in part because of counter-current vascular heat exchange systems in their legs and nasal passages.

2013 March, Nancy Langston, “Mining the Boreal North”, in American Scientist‎, volume 101, number 2, archived from the original on 13 April 2016, page 98