What is 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.] called?

coak — (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.]. (Webster's 1913.)