Imperishingness is a rare and complex word used to describe something that will never perish or decay. Although there are not many synonyms for this word, some options include durability, indestructibility, longevity, and eternalness. These words all convey a similar meaning, describing something that will last forever and will not be destroyed by the passage of time or other external forces. Another term that might be used in place of imperishingness is immortality, which implies that the object, idea, or concept will live on indefinitely, outside the bounds of mortality and physical decay. Ultimately, any of these phrases might be used in place of imperishingness, depending on the context and intent of the writer or speaker.