rarefy

• vt. 使纯化；变稀薄；精选
• vi. 变稀薄；纯化

来自 rare,稀薄的，罕见的，-fy,使。引申词义使精深，使高雅。

rarefy (v.)

late 14c., from Old French rarefier (14c.) and directly from Medieval Latin rarificare, from Latin rarefacere "make rare," from rarus "rare, thin" (see rare (adj.1)) + facere "to make" (see factitious). Related: Rarefied.