When it comes to unpleasant smells, the phrase "noxious stench" is often used. However, there are many other synonyms that can be used to describe offensive odors. Some possibilities include "foul odor," "disgusting aroma," "repulsive scent," "rank smell," "putrid stink," "revolting pong," "offensive stink," and "nauseating fragrance." Depending on the context and the severity of the smell, there are many different words that can be used to convey the level of discomfort and disgust that a person might feel. Whether it's in a rotten garbage can or a stagnant pool of water, these synonyms can help to paint a more vivid picture of the olfactory assault that is taking place.