MustyMUS'TY, adjective [from must.] Moldy; sour; foul and fetid; as a musty cask; musty corn or straw; musty books.1. State; spoiled by age.The proverb is somewhat musty2. Having an ill flavor; as musty wine.3. Dull; heavy; spiritless.That he may not grow musty and unfit for conversation.