what is a tidalwave?

Answer 1

From Wikipedia:

A tsunami. "Tidal wave" is a common, traditional name for the occurrence, but considered incorrect by oceanographers, seismologists and other scientists since no tides are involved. (However, "tidal" can be thought to refer to the magnitude rather than the nature or the origin of the wave.) The term "tidal wave" was much more familiar to the general public than "tsunami" before the 2004 Indian Ocean tsunami, but news media reports of this disaster used "tsunami" almost exclusively and so it has become better known.

Answer 2

The term 'tidal wave' is used in everyday speech to refer to a gigantic and enormously destructive wave caused by an underwater earthquake or volcanic eruption—what scientists would properly call a tsunami. When scientists use the word tidal wave, they normally are referring to an unusually large wave or bulge of water that sometimes occurs around a high tide. These tidal waves are certainly big and powerful, but they are tiny in comparison with tsunamis.

'Tidal wave' was used to describe a tsunami that occurred after the eruption of Krakatau, Indonesia in 1883 in newspapers around the world.

Answer 3

Tidal waves refer to unusually large waves, not necesarily tsunamies. There are also king tides that produce high waves that can do serious erosion to foreshores, but are not necesarily life-threatening.