TidalStream Share definition Flag A term used for the boundary area of the waves while tubing behind a boat. Interestingly, The word "Tidal" Nor "Stream" have anything to do with the aforementioned term. You dude, That TidalStream is Huge!We would've had a big bump if we crossed that! TidalStream by Aerly July 22, 2022 Get the TidalStream mug.