topmast noun. ['tɒpmɑ:st, -mǝst] L15.
[from TOP adjective + MAST noun¹.]
Nautical. A mast attached to the top of a lower mast; spec. the second section of a mast above the deck, formerly the uppermost mast, later surmounted by the topgallant mast.

[TahlilGaran] English Dictionary ▲