rar·e·fied also rar·i·fied (râr′ə-fīd′)
adj.
1. Not dense; thin: the rarefied air of the high peaks.
2. Belonging to or reserved for a small select group; exclusive: accepted in the most rarefied social circles.
3. Refined or esoteric: rarefied academic theorizing; a man of rarefied appetites.