/bon"euh ven'cheuhr, bon'euh ven"-/ , n. Naut.
a mast fitted with a lateen sail (bonaventure mizzen) or lugsail, situated behind the mizzenmast at or near the stern, used in the 16th and early 17th centuries.
[ 1490-1500; buonaventura lit., good luck. See BONUS, VENTURE ]