Definition of unbelievably

"Unbelievably" is a compound word formed by combining the prefix "un-" meaning "not" with the adjective "believable." The word "believable" itself originated from the Old French word "believable," which comes from the Latin word "credibilis," meaning "worthy of belief." Therefore, "unbelievably" literally means "not worthy of belief" or "impossible to believe." The word likely emerged in the late Middle Ages or early Modern English period, as the combination of prefixes and base words became more common.