means To scatter liquid about noisily, or the sound and mark made when something hits water — and by extension, a sudden striking display, as in 'making a splash.'

from An English word of imitative origin — it simply sounds like what it does, the spluttering smack of water flung apart. It appears as a more emphatic cousin of the older 'plash,' which described the gentler patter of liquid. Stick an 's' on the front, as English loves to do for extra force, and the modest 'plash' becomes a fuller, wetter 'splash.'