When something is no longer at its peak, there are many synonyms to describe it. One common phrase is "past its prime", which can have negative connotations. Other phrases that can be used to describe this state of being include "past its heyday", "past its glory days", or simply "past its best". Other words that can be used as synonyms include "outdated", "obsolete", "antiquated", "quaint", "old-fashioned", "vintage", "retro", and "dated". All of these words imply that something was once great, but has since fallen from grace. While some might view this state of being as a negative thing, others may find beauty in things that are no longer modern or popular.