The Collaborative International Dictionary of English v.0.48:

Tenon \Ten"on\, v. t.
   To cut or fit for insertion into a mortise, as the end of a
   piece of timber.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tenon \Ten"on\, n. [F., fr. tenir to hold. See Tenable.]
   (Carp. & Join.)
   A projecting member left by cutting away the wood around it,
   and made to insert into a mortise, and in this way secure
   together the parts of a frame; especially, such a member when
   it passes entirely through the thickness of the piece in
   which the mortise is cut, and shows on the other side. Cf.
   Tooth, Tusk.
   [1913 Webster]

   Tenon saw, a saw with a thin blade, usually stiffened by a
      brass or steel back, for cutting tenons. [Corruptly
      written tenant saw.] --Gwilt.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tenon
    n 1: a projection at the end of a piece of wood that is shaped
         to fit into a mortise and form a mortise joint