The Collaborative International Dictionary of English v.0.48:
Oast \Oast\ ([=o]st), n. [OE. ost, AS. [=a]st; cf. Gr. a'i^qos burning heat.] A kiln to dry hops or malt; a cockle. --Mortimer. [1913 Webster]WordNet (r) 3.0 (2006):
oast n 1: a kiln for drying hops