Mast head is English. It's the top of a mast.
the lookout who was stationed at the top of the mast
The main mast is the tallest of all masts on the ship. If all masts are the same height, then the one with the top navigationlight is the main mast. If there is only one mast, then that would be the main mast.
masthead
The symbol for a radio mast on an ordinance survey map is typically a triangle with a line through the top, representing the mast structure. It is often accompanied by a small circle to indicate the location of the mast.
The mizzen is the third mast on a ship, or the mast immediately aft of the mainmast. The top sail on that mizzenmast would the mizzen-top. Your local slang may vary.
23.2 ft.
Top of the head
it is a nut that holds the main rotor to the mast of some helicopters. The Jesus Nut is the large nut on the top of the mast that holds the entire rotor blades and rotor mechanism to the mast. Bascially, it holds the weight of the aircraft by the top of the mast and if it should fail, then all you can do is say "Jesus!".
The flag must first be hoisted to the top of the mast momentarily, and then it is lowered to the half mast position and secured.
Crow's nest
The extended height when forks are at top.