1. Any animal; especially, a wild animal. Mice and rats, and such small deer. (Shak) The camel, that great deer. (Lindisfarne MS)
2. (Science: zoology) a ruminant of the genus Cervus, of many species, and of related genera of the family Cervidae. The males, and in some species the females, have solid antlers, often much branched, which are shed annually. Their flesh, for which they are hunted, is called venison.
The deer hunted in England is Cervus elaphus, called also stag or red deer; the fallow deer is c. Dama; the common American deer is c. Virginianus; the blacktailed deer of western North America is c. Columbianus; and the mule deer of the same region is c. Macrotis. See axis, fallow deer, mule deer, reindeer.
deer is much used adjectively, or as the first part of a compound; as, deerkiller, deerslayer, deerslaying, deer hunting, deer stealing, deerlike, etc.
(Science: zoology) deer mouse, the white-footed mouse (Hesperomys leucopus) of America. Small deer, petty game, not worth pursuing; used metaphorically. (see citation from Shakespeare under the first definition, above) Minor critics . . . Can find leisure for the chase of such small deer.
Origin: oe. Der, door, animal, wild animal, as. Deor; akin to D. Dier, OFries. Diar, g. Thier, tier, Icel. Dr, dan. Dyr, Sw. Djur, goth. Dius; of unknown origin.