Source : Webster's Revised Unabridged Dictionary (1913)

Coak \Coak\, n.
   1. (Carp.) A kind of tenon connecting the face of a scarfed
      timber with the face of another timber, or a dowel or pin
      of hard wood or iron uniting timbers. [Also spelt {coag}.]

   2. A metallic bushing or strengthening piece in the center of
      a wooden block sheave.

Coak \Coak\ (k[=o]k), n.
   See {Coke}, n.

Coak \Coak\, v. t. (Carp.)
   To unite, as timbers, by means of tenons or dowels in the
   edges or faces. --Totten.