Reverb is a type of natural effect you can get playing in walled spaces, giving a sort of echo/reverberation as the name implies. But I'm referring more to emulated reverb through use of a guitar pedal or other processor.
Many people refer to reverb as "drippy" or "wet" when dialed to 11. I think usually referring to spring reverb (where old reverb units used springs to get that sound). I naively once believed 'spring reverb' meant 'reverb as though you were playing in a water spring' before learning it meant actual springs.
But where does the water metaphor come from? My best guess was reverb became a mainstay of American rock-and-roll with bands like The Beach Boys, where reverb was used heavily. I usually associate heavy reverb with surf rock. Could this be where the water metaphor comes from?
Many musicians also describe their signals as "wet" or "dry", as some kind of spectrum. There's a lot of instances where "wet", "drippy", "soaked", etc come up and I wonder if they all share a common source.