Definition of "wing-sail" [wing-sail]

• The foresail or the mainsail of a schooner: so called because when the schooner is running before the wind these sails are often boomed out on opposite sides of the vessel, which is then said to be sailing wing-and-wing. (noun)

The Century Dictionary (Public Domain)

• "BMW Oracle, owned by US software tycoon Larry Ellison, claim their boat USA, featuring a wing-sail twice the size of that on a Boeing 747 plane, can reach speeds of 40 knots and slice along with one hull lifted 30 feet in the air."
• "Powered by its wing-sail, Oracle extended its lead over Alinghi over the next two legs, clocking a speed of 33 knots at one point with its owner Larry Ellison onboard in the afterguard position as a late addition to the crew."
• "Oracle's Auckland-based mastman Matthew Mason agreed the swell would be the determining factor in whether the US-Challengers 'wing-sail powered triamaran USA-17 and the Swiss syndicates' catamaran Alinghi 5 are finally unleashed."