slide, glide, slip, slippery
澑 centers on smooth, effortless motion across a surface: sliding, gliding, or slipping. The idea extends to anything that is slippery or causes slipping.
澑 is the traditional form of 溜. It combines 氵 (water) with 畱, which likely contributes the sound and the idea of staying or remaining, suggesting water that slides or collects.
Water 氵 beside 畱: picture a water slide where water makes the surface slippery so you can glide down smoothly.
For リュウ, imagine sliding on a wet surface and saying 'ryuu' as you glide: the smooth sound cues リュウ while you slip along.