tidal wave

ot noun

1. 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.
2. A sudden and powerful surge. As the doors opened, a tidal wave of people flooded into the room.
3. A large and sudden rise and fall in the tide.
4. A large, sudden inundation of water from the storm surge, or waves of that surge.