The word "rotten" can be interchanged with several other words to convey a similar meaning. Some of the synonyms include spoiled, decayed, putrid, decomposed, fetid, rancid, and sour. Each word describes something that is not fresh or healthy and can be used to describe anything from food to a situation that has become unpleasant. For example, you might describe a foul smell as fetid, or a situation that is no longer enjoyable as rotten. Choosing the right synonym for the situation can help to create vivid descriptions and more effective communication.