Long-lost is an adjective used to describe something that has been missing or lost for a long period of time. However, there are other synonyms that can be used interchangeably with this term. For instance, the term forgotten describes something that has been abandoned and neglected. Similarly, the term misplaced denotes something that has been put in the wrong place or lost track of. Alternatively, the phrase "ancient relic" connotes an object of value that has been lost for an extended period, and the term "vanished" describes something that has disappeared without a trace. Ultimately, using these synonyms helps to add variety to written and spoken language and makes communication more effective.