IPA: /ˈrɛəfəˌfaɪd/
KK: /ˈrɛrɪfaɪd/
Belonging to a small, select group or having a high level of quality or style; often used to describe something that is not common or is more refined.
The rarefied atmosphere of the exclusive club made it difficult for newcomers to fit in.
Rarefied → It is formed from "rarefacere" (meaning to make rare or thin) and the suffix "-ed" (indicating a state or condition). The word "rarefied" means made rare or less dense, often used in the context of air or atmosphere.
Think of something being 'made rare' or 'thinned out' — that's why rarefied describes something that is less dense or more refined.