tidal wave

Noun

tidal wave (plural tidal waves)

1. A large and sudden rise and fall in the tide.
2. (proscribed) A large, sudden, and disastrous wave of water caused by a tremendous disturbance in the ocean; a tsunami. (See Usage notes below.)
   • The last tidal wave here killed twenty and left thousands homeless.
3. (proscribed) A large, sudden inundation of water from the storm surge, or waves of that surge; a sudden surge of river water.
   • During the day conditions worsened quickly—for example, a 2-6-0 on the Uckfield line suddenly encountered flood water high enough to enter its ashpan and extinguish its fire—until lock gates up-river at Barcombe gave way and a tidal wave rolled down the valley meeting head-on a spring tide rolling...1961 January, “Talking of Trains: Flooding at Lewes”, in Trains Illustrated, page 5
4. (figuratively) A sudden and powerful surge.
   • As the doors opened, a tidal wave of people flooded into the room.
   • I was overcome by a tidal wave of emotions.
5. (archaic) A crest of ocean water; a wave.
6. A crest of ocean water resulting from tidal forces.