1. Action de raréfier, de se raréfier.
2. Résultat de cette action.
ETYM Cf. French raréfaction. Related to Rarefy.
1. The action or process of rarefying.
2. The quality or state of being rarefied.
3. A state or region of minimum pressure in a medium traversed by compressional waves (as sound waves).
4. A decrease in the density of something.