A strip of wood or iron fastened on transversely to something in order to give strength, prevent warping, hold position, etc. [1913 Webster]
A device made of wood or metal, having two arms, around which turns may be taken with a line or rope so as to hold securely and yet be readily released. It is bolted by the middle to a deck or mast, etc., or it may be lashed to a rope. [1913 Webster]
cleat, n.
1 a piece of metal, wood, etc., bolted on for fastening ropes to, or to strengthen woodwork etc.
2 a projecting piece on a spar, gangway, boot, etc., to give footing or prevent a rope from slipping.
3 a wedge.