from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A decrease in density and pressure in a medium, such as air, caused by the passage of a sound wave.
- n. The region in which this occurs.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a reduction in the density of a material, especially that of a fluid
from the GNU version of the Collaborative International Dictionary of English
- n. The act or process of rarefying; the state of being rarefied; -- opposed to condensation.
from The Century Dictionary and Cyclopedia
- n. The act or process of rarefying or making rare, or of expanding or distending a body or mass of matter, whereby the bulk is increased, or a smaller number of its particles occupy the same space; also, the state or condition so produced: opposed to condensation.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a decrease in the density of something
Sorry, no etymologies found.