"NOT FOUND" is a common error message that indicates the inability to find the desired item. There are several synonymous terms available for it. One of the most commonly used synonym is "not located", which means the same thing but sounds a little less harsh than "not found." Other synonyms include "missing," "absent," "unavailable," "undiscovered," "non-existent," "out of reach," and "beyond reach". When encountering such an error message, it is essential to double-check the spelling and make sure the item is still available. These synonyms can be used interchangeably and help improve the user experience by providing a friendly and clear message indicating the reason why the search is unsuccessful.