n. The quality or state of being foul or filthy; impurity; filthiness; defilement; pollution; corruption: as, the foulness of a cellar or of a well; the foulness of a musket: the foulness of a, ship's bottom.n. Ugliness; deformity.n. Unfairness; dishonesty; atrociousness; villainy; treachery; abusiveness; scurrility: as, the foulness of a blow or a scheme; the foulness of a slander or crime.