reindeer UK /ˈɹeɪndɪə/US /ˈɹeɪndɪɹ/noun 2verb 1forms 3 noun2 •Any Arctic and subarctic-dwelling deer of the species Rangifer tarandus, with a number of subspecies.Santa Claus' sleigh is supposedly pulled by nine reindeer •Any species, subspecies, ecotype, or other scientific grouping of such animals. verb1 •To herd or farm reindeer formsreindeered · reindeering · reindeers