[1] : The Collaborative International Dictionary of English v.0.48

wapiti \wap"iti\, n. probably the iroquois name. bartlett.
   zool.
   the american elk cervus canadensis. it is closely related
   to the european red deer, which it somewhat exceeds in size.
   1913 webster

   note: by some writers it is thought to be a variety of the
         red deer, but it is considered a distinct species by
         others. it is noted for the large, branching antlers of
         the male.
         1913 webster
see also:
cervus canadensis 

[2] : The Collaborative International Dictionary of English v.0.48

elk \elk\ e^lk, n. icel. elgr; akin to sw. elg, as. eolh,
   ohg. elaho, mhg. elch, cf. l. alces; perh. akin to e. eland.
   zo"ol.
   a large deer, of several species. the european elk alces
   alces formerly alces machlis or cervus alces is
   closely allied to the american moose. the american elk, or
   wapiti cervus canadensis the largest member of the deer
   family, has large, spreading antlers and is closely related
   to the european stag. see moose, and wapiti.
   1913 webster +pjc

   irish elk paleon., a large, extinct, quaternary deer
      cervus giganteus with widely spreading antlers. its
      remains have been found beneath the peat of swamps in
      ireland and england. see illustration in appendix; also
      illustration of antler.

   cape elk zo"ol., the eland. elk
see also:
alces alces alces machlis cervus alces cervus canadensis moose wapiti 
irish elk cervus giganteus antler cape elk 

[3] : WordNet (r) 2.0

cervus canadensis
     n : large north american deer with large much-branched antlers
         syn: wapiti, american elk
see also:
wapiti american elk 

Cervus >> C Words
Cervus, definition of term: Cervus
cervus_pag1.html

Canadensis >> C Words
Canadensis, definition of term: Canadensis
canadensis_pag1.html