rarify

/ˈrɛrəˌfaɪ/
verb
  1. To make less dense, especially to thin out air or gas.
    • As you climb higher, the atmosphere rarifies naturally.
    • The vacuum pump rarifies the air inside the chamber.
    • Scientists rarify the gas to study its behavior under low pressure.
  2. To refine or make more exclusive or esoteric.
    • The club's strict membership rules rarify its social circle.
    • They sought to rarify the language of the poem, making it harder for casual readers.
    • Over time, the artist's style became more rarified and abstract.
Antonyms