MUSTY Meaning of MUSTY in English a. 1.Mouldy, fusty, sour, fetid, rank, foul, spoiled, stale, frowzy.2.Stale, old, hackneyed, trite, threadbare.3.Vapid, ill-flavored, stale, insipid.4.Dull, heavy, spiritless, rusty. Soule. Dictionary of English synonyms. Словарь английских синонимов. 2012