tsunami: [19] Japanese tsunami means literally ‘harbour waves’, a reference to the devastating effect Pacific tsunamis have had on Japanese coastal communities. For most of the 20th century the term was largely restricted to the specialized vocabulary of oceanographers and earth scientists, lay people preferring the more familiar tidal wave (a misnomer: strictly speaking, a tidal wave is one caused by the movement of the tide, whereas a tsunami is specifically generated by an undersea earthquake), but the disastrous inundation of southern Asian coasts at the end of 2004 lodged it firmly in the language’s everyday lexicon. [tsunami etymology, tsunami origin, 英语词源]