Definitions
1.nounA large and sudden rise and fall in the tide.
2.nounA 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.nounA large, sudden inundation of water from the storm surge, or waves of that surge.
4.nounA sudden and powerful surge."As the doors opened, a tidal wave of people flooded into the room."
5.nounA crest of ocean water; a wave.
6.nounA crest of ocean water resulting from tidal forces.