The antonyms for the word "sweet smelling" are unpleasant, rancid, putrid, foul, stinking, rank, acrid, and malodorous. While sweet-smelling brings a pleasant aroma, the antonyms refer to the opposite. For instance, unpleasant odor indicates something that produces a disagreeable smell, while rancid suggests something that has gone bad and produces a sharp, sickly smell. Putrid suggests the smell of decaying matter or spoiled food, while foul refers to something that gives off an offensive, rotten odor. Stinking indicates a strong and unpleasant smell and rank smell indicates something that is offensively impure. Acrid and malodorous suggest an irritating or unpleasant smell.