Most perduring is a term used to describe something that endures or lasts for a long time. Antonyms for this phrase could include words such as transitory, fleeting, temporary, ephemeral, or impermanent. These words describe things that are short-lived, passing, or not long-lasting. Most perduring, on the other hand, implies something that is durable, unchanging, and has a long-term impact. While the antonyms suggest something more temporary, they can also imply something that is less significant or less impactful. Therefore, it's essential to consider the context in which these antonyms are used and the implications they may have.