What is "tenon saw"

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.

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

n. A fine, precision saw with a metal strip to provide stiffening along its back; used to make tenons and other joints