Bucentaur (Ital. bucintoro), the state gallery of the doges of Venice, on which, every year on Ascension day up to 1789, they put into the Adriatic in order to perform the ceremony of "wedding the sea." The name bucintoro is derived from the Ital. buzino d' oro, "golden bark," latinized in the middle ages as bucentaurus on the analogy of a supposed Gr. βουκένταυρος, ox-centaur (from βοῦς and κένταυρος). This led to the explanation of the name as derived from the head of an ox having served as the galley's figurehead. This derivation is, however, fanciful; the name bucentaurus is unknown in ancient mythology, and the figurehead of the bucentaurs, of which representations have come down to us, is the lion of St Mark. The name bucentaur seems, indeed, to have been given to any great and sumptuous Venetian galley. Du Cange (Gloss., s.v. "Bucentaurus") quotes from the chronicle of the doge Andrea Dandolo (d. 1354): cum uno artificioso et solemni Bucentauro, super quo venit usque ad S. Clementem, quo jam pervenerat principalior et solemnior Bucentaurus cum consiliariis, etc.

The last and most magnificent of the bucentaurs, built in 1729, was destroyed by the French in 1798 for the sake of its golden decorations. Remains of it are preserved at Venice in the Museo Civico Correr and in the Arsenal; in the latter there is also a fine model of it.

The "Marriage of the Adriatic," or more correctly "of the sea" (Sposalizio del Mar) was a ceremony symbolizing the maritime dominion of Venice. The ceremony, established about A.D. 1000 to commemorate the doge Orseolo II.'s conquest of Dalmatia, was originally one of supplication and placation, Ascension day being chosen as that on which the doge had set out on his expedition. The form it took was a solemn procession of boats, headed by the doge's maesta nave, afterwards the Bucentaur (from 1311) out to sea by the Lido port. A prayer was offered that "for us and all who sail thereon the sea may be calm and quiet," whereupon the doge and the others were solemnly aspersed with holy water, the rest of which was thrown into the sea while the priests chanted "Purge me with hyssop and I shall be clean." To this ancient ceremony a sacramental character was given by Pope Alexander III in 1177, in return for the services rendered by Venice in the struggle against the emperor Frederick I. The pope drew a ring from his finger and, giving it to the doge, bade him cast such a one into the sea each year on Ascension day, and so wed the sea. Henceforth the ceremonial, instead of placatory and expiatory, became nuptial.

Every year the doge dropped a consecrated ring into the sea, and with the words Desponsamus te, mare (We wed thee, sea) declared Venice and the sea to be indissolubly one (see H. F. Brown, Venice, London, 1893, pp. 69, 110).