silica gel

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Amorphous silica that resembles fine white sand and is used as a drying and dehumidifying agent, as a catalyst and catalyst carrier, as an anticaking agent in cosmetics, and in chromatography.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry a granular, porous form of silica made synthetically from sodium silicate and used as a desiccant.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a porous form of silica that is highly absorbent