The story
- Latin · derived fromrarefacere“make rare”
- Old French · derived fromrarefier
- Middle English · inherited fromrarefien
- English todayrarefy
From Middle English rarefien, from Old French rarefier (French raréfier), from Latin rarefacere (“make rare”). By surface analysis, rare + -fy.
Etymology from Wiktionary, CC BY-SA 4.0.