Source : Webster's Revised Unabridged Dictionary (1913)

Kayak \Kay"ak\, n. (Naut.)
   A light canoe, made of skins stretched over a frame, and
   usually capable of carrying but one person, who sits
   amidships and uses a double-bladed paddle. It is peculiar to
   the Eskimos and other Arctic tribes.

Source : WordNet®

kayak
     n : a small canoe consisting of a light frame made watertight
         with animal skins; used by Eskimos
     v : travel in a small canoe; "we kayaked down the river"