mustiness n the quality of smelling or tasting old or stale or mouldy Usage(s) The venerable institution has thrown off its quaint mustiness and become one of Europe's most inviting cultural attractions. Gradually, with the passage of years, its mustiness changes to a delicate old-fashioned odor. Matisse did much, at the beginning of this century, to dispel the mustiness of academic art. Synonym(s) must moldiness