reindeer (n.) Look up reindeer at Dictionary.com
c.1400, from Old Norse hreindyri "reindeer," from dyr "animal" (see deer) + hreinn, the usual name for the animal, from Proto-Germanic *khrainaz (cf. Old English hran "reindeer," German Renn). Probably cognate with Greek krios "ram," but folk etymology associates it with rennen "to run."