tidal wave

Short definition from Wiktionary

Noun

1. 1
   A large and sudden rise and fall in the tide.
2. 2
   A large, sudden, and disastrous wave of water caused by a tremendous disturbance in the ocean; a tsunami. (See Usage notes below.)
3. 3
   A large, sudden inundation of water from the storm surge, or waves of that surge; a sudden surge of river water.
4. 4
   A sudden and powerful surge.
5. 5
   A crest of ocean water; a wave.
6. 6
   A crest of ocean water resulting from tidal forces.