the.com/water slide

means A steep wet chute, usually at a pool or amusement park, that you ride down on water's momentum alone, for thrills.

from Simply a compound of 'water' and 'slide' — 'slide' tracing back to Old English 'slidan,' meaning to glide or slip. No exotic backstory here: purpose-built water slides emerged as pool and amusement-park attractions in the 20th century, scaling up the age-old human impulse to find a wet surface and go fast on it.