|rarefaction or rarefication (ˌrɛərɪˈfækʃən, ˌrɛərɪfɪˈkeɪʃən)|
|the act or process of making less dense or the state of being less dense|
|rarefication or rarefication|
|rare'factional or rarefication|
|rarefi'cational or rarefication|
|rare'factive or rarefication|
rarefaction rar·e·fac·tion (râr'ə-fāk'shən)
A decrease in density and pressure in a medium, such as air, caused by the passage of a sound wave.