Learner's definition of PUMICE
[noncount]
: a gray stone that comes from volcanoes, is full of small holes, has a very light weight, and is used especially for smoothing and polishing things or for softening the skin浮石，浮岩（一种火山灰岩石，尤用于抛光物体或使皮肤光滑） — called also pumice stone