Etymology of the English word rarefy
the English word rarefy
derived from the Old French word rarefier
derived from the Latin word rarefacere (make less solid)
derived from the Latin word facere (to make; act, take action, be active; compose, write; classify; do, make; create; make, build, construct; produce; produce by growth; bring forth)
derived from the Proto-Indo-European root *dhē-
derived from the Latin word rarus (thin, scattered; few)