a cataclysm resulting from a destructive sea wave caused by an earthquake or volcanic eruption
"a colossal tsunami destroyed the Minoan civilization in minutes"
A very large and destructive wave, generally caused by a tremendous disturbance in the ocean, such as an undersea earthquake or volcanic eruption. Tsunami are usually a series of waves, or wave train.
"The powerful tsunami that struck the coast after the massive undersea earthquake destroyed entire villages with its towering walls of water."
In plain English: A tsunami is a huge ocean wave caused by underwater earthquakes, volcanic eruptions, or landslides that can destroy everything on shore when it reaches land.
"The powerful tsunami destroyed several coastal villages along the shore."
Usage: A tsunami is specifically generated by underwater disturbances like earthquakes rather than strong winds. Do not use this term to describe regular storm waves that form from atmospheric conditions.
The word tsunami comes directly from the Japanese phrase tsun nami, which literally means "port wave." It entered English to describe large ocean waves that are often triggered by underwater earthquakes or volcanic eruptions.