Etrigan is an obscure word that is rarely used in modern English. It is the name of a demon in medieval literature and popularized in DC Comics as a character. However, if you're looking for synonyms for Etrigan, there are few options. One alternative may be "demon" or "devil" as these are terms used to describe similar beings. Another possibility is "infernal" or "hellish" which expresses the otherworldly nature associated with Etrigan. Alternatively, you could use terms like "enigmatic", "mysterious" or "uncanny" to capture the eerie and supernatural qualities of Etrigan. Overall, Etrigan is quite a unique word, so sourcing synonyms may result in a less accurate description.