|ra(a)rə|fakshən, |rer- noun
( -s )
Etymology: French or Medieval Latin; French raréfaction, from Middle French rarefaction, from Medieval Latin rarefaction-, rarefactio, from Latin rarefactus (past participle of rarefacere to rarefy) + -ion-, -io -ion — more at rarefy
1. : the act or process of rarefying
2. : the quality or state of being rarefied
rarefaction of bone
3. : a state or region of minimum pressure in a medium transversed by compression waves (as sound waves) — compare condensation 4b
• rar·e·fac·tion·al -shən ə l, -shnəl adjective