Word Origin & History
deer
O.E. deor "animal, beast," from P.Gmc. *deuzan, the general Gmc. word for "animal" (as opposed to man), but often restricted to "wild animal" (cf. O.N. dyr, O.H.G. tior, Ger. Tier, Goth. dius), from PIE *dheusom "creature that breathes," from *dheus- (cf. Lith. dusti "gasp," dvesti "gasp, perish;" O.C.S. dychati "breathe;" cf. L. animal from anima "breath"), from base *dheu-. Sense specialization to a specific animal began in O.E. (usual O.E. for what we now call a deer was heorot), common by 15c., now complete. Probably via hunting, deer being the favorite animal of the chase (cf. Skt. mrga- "wild animal," used especially for "deer"). Deer-lick is first attested 1778, in an American context; deerskin is from 1396.
[deer] 
) deers.