rarefaction (n.)youdaoicibaDictYouDict[rarefaction 词源字典]
c. 1600, from Middle French raréfaction or directly from Medieval Latin rarefactionem (nominative rarefactio), noun of action from past participle stem of Latin rarefacere (see rarefy). Used chiefly in reference to gases.[rarefaction etymology, rarefaction origin, 英语词源]