rar ‧ e ‧ fied /ˈreərəfaɪd, ˈreərɪfaɪd $ ˈrer-/ BrE AmE adjective [usually before noun]
1 . a rarefied place, organization, or type of activity is only available to or understood by a small group of people – used to show disapproval:
the rarefied atmosphere of academia
2 . rarefied air is the air in high places, which has less oxygen than usual