What is the meaning of Tenon?

A projecting member left by cutting away the wood around it, and made to INSERT IGNORE 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.

Source: Webster’s Revised Unabridged Dictionary (1913), via OPTED