A substance capable of adsorbing. A natural or artificial finely porous solid with a large external and (or) an inner surface, where the adsorption of gases or liquids flows.
The formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids implode and can generate an intense shockwave.