#1 hydroplane n. [seaplane] an airplane that can land on or take off from water; "the designer of marine aircraft demonstrated his newest hydroplane". wn
#2 hydroplane v. [seaplane] glide on the water in a hydroplane. wn
#3 hydroplane n. [hydrofoil] 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". wn
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