The hole drilled through a mortise and tenon joint in draw boring. Also (and earliest) as a modifier, especially in "drawbore pin" noun (a) a tool consisting of a tapered metal shaft, used in draw boring to bring the parts of the joint together and align the holes before the wooden peg is driven in; (b) the wooden peg itself.

To pin together (a mortise and tenon joint, or its parts) by drilling a hole through the joint and driving a wooden peg into it. Also: to drill a drawbore or use a drawbore pin in. Compare drawbore, draw boring.