Ost rhymes with:
boast, coast, coste, diagnosed, droste, engrossed, ghost, grossed, host, ivory-coast, khost, most, post, riposte, roast, toast, toste, voest, woeste, yoast, yost
Ost sounds like:
oakite, oakwood, oct, oct., octet, oest, ogata, ojeda, okada, okayed, okdo, okuda, oozed, osgood, oshita, ossetia, ostia, ought, oughta, oust, ousted, oxide