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; a sudden surge of river water.
4.NounA 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.NounA crest of ocean water; a wave.
6.NounA crest of ocean water resulting from tidal forces.