On a sailing boat, this refers to the pole from which the sails are rigged. A motor cruiser may have a mast
that is no longer than a sailing cruiser’s ensign staff, but it is still called
a mast. A mast has a Head at the top and a Foot at the bottom. The head of a
wooden mast is usually capped with a disc called the Truck which covers the
exposed end-grain of the mast itself against water. A mast is supported by
Shrouds and Stays, and it may have Spreaders to spread the shrouds and widen
their angle of pull. Lower shrouds meet the mast at the roots of the spreaders,
and this region is called the Hounds. The foot of the mast may step on deck in
a large socket structure called a Tabernacle, or it may pass right through the
deck and be stepped on the keel itself. Note that a mast steps on things with
its foot, and that the after part of the underside of the foot is even called
its Heel.