Definition of "mizzenmast"

(nautical) The aftmost mast on a ship having three masts; the third-tallest mast on a full-rigged ship.  examples

(nautical) The third-foremost mast on a ship having more than three masts.  examples

(nautical) The second mast of a ship having two masts where the second one is shorter, such as a ketch or yawl.  examples