"Belfagor" is a term that refers to a demonic figure in Italian folklore. While there are no direct synonyms for this term, there are numerous other words that can refer to demonic or malevolent entities. Some examples of such words include devil, demon, fiend, evil spirit, malignant force, hellspawn, and wicked entity. While there may be subtle differences in connotation and context between these various synonyms, they all share the common theme of describing something that is malevolent or demonic in nature. Whether used in literature, folklore, or spoken language, these synonyms can help to convey a sense of darkness and fear.