Definitions for "Aerogel"
The lightest known sponge-like solid made mostly of air and a small amount of silicon (sand). Referenced in: StarDust Why Comet Wild-2
Very low density material with very high internal porosity.
A porous solid formed by replacing the liquid in a gel with a gas; what remains when the liquid part of an alcogel is removed without damaging the solid part.
a type of xerogel from which the liquid has been removed in such a way as to minimize any collapse or change in the structure as the water is removed