adjective

1. Distant from the lives and everyday concerns of ordinary people; esoteric, exclusive, select.

   “Philosophical debates can be quite rarefied.”

2. Elevated in style or nature, sublime; of high intellectual or moral value.

3. (of a gas etc.) Less dense than usual; thin.

   “The air at high altitudes at the top of mountains is rarefied.”

verb

1. To make rare, thin, porous, or less dense

2. To expand or enlarge without adding any new portion of matter to.

Synonyms: stretch