Tsunami - Wikipedia A tsunami ( (t) s uː ˈ n ɑː m i, (t) s ʊ ˈ- (t)soo-NAH-mee, (t)suu-; [1] [2] [3] [4] from Japanese: 津波, lit 'harbour wave', [5] pronounced) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake