topmast
top.mast \'ta:p-.mast, -m*st\ n : the mast that is next above the lower mast and topmost in a fore-and-aft rig
Webster's English Dictionarytop.mast \'ta:p-.mast, -m*st\ n : the mast that is next above the lower mast and topmost in a fore-and-aft rig