Definition - What does Tsunami mean?
A tsunami is a natural disaster characterized by very large wave which is caused by an underwater earthquake or volcanic eruption and often causes extreme destruction when it strikes land. Tsunami is a Japanese word which is literally translated as "harbor wave" in English. It is represented with two characters. The top character "Tsu" means harbor, while the bottom character "Nami" means wave.
Safeopedia explains Tsunami
Tsunamis can reach as high as 30 metres or 98 feet and move as fast as 950 km or 589 miles per hour. The length of a tsunami wave can be up to 200 km or 124 miles, and can last from 10 to 60 minutes when striking land. They are also incorrectly called tidal waves even though they are not tidal. Tidal waves are caused by the gravitational interactions of the sun, moon and earth rather than seismic influences as with tsunamis.