Reverseless is a word used to describe a situation or action that cannot be undone or reversed. However, if you're looking for synonyms to describe the same concept, you can use terms like irreversible, irrevocable, unrecoverable, irretrievable, permanent or final. These words indicate that once something is done, there is no turning back, and it is impossible to undo or reverse it. In contrast, reversible, revocable, recoverable, retrievable, and temporary suggest that something can be undone or changed back to its original state without any permanent damage. Therefore, if you want to emphasize the irreversible nature of a situation or decision, you can use any of these synonyms instead of reverseless.