On the way out is a popular phrase that is used to describe something or someone that is in the process of declining or becoming less successful. There are many synonyms for this phrase that can be used, depending on the context. Some of the most common synonyms for on the way out include declining, fading, waning, diminishing, deteriorating, dwindling, and ebbing. Other possible synonyms might include losing popularity, losing steam, losing ground, or losing momentum. Regardless of the specific synonym that is used, the overall meaning remains the same: something is in the process of declining or fading away.