IPA: /ˈoʊsˌhaʊs/
KK: /ˈoʊsˌhaʊs/
A building used for drying hops as part of the brewing process.
The old oasthouse was converted into a cozy guest house.
Oasthouse is formed from "oast" (from Old English *āst*, meaning a kiln for drying hops or malt) and "house" (from Old English *hus*, meaning a dwelling or shelter). An oasthouse is a building specifically designed for drying hops used in brewing beer.
Imagine a 'house' where hops are 'dried' — that's what an oasthouse is used for.