1. (

• hydrofoil ,
• foil ,

) a device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through; "the fins of a fish act as hydrofoils" ;

2. (

• hydrofoil ,
• hydroplane ,

) a speedboat that is equipped with winglike structures that lift it so that it skims the water at high speeds; "the museum houses a replica of the jet hydroplane that broke the record" ;