Church Slavonic sanĭ, snŭ, sanŭ 'dragon (= devil)' is used in the translation of Isaiah´s Prophecy (Is 27,1) instead of Greek ofis 'snake'. In both cases these are substitutions of a taboo term for devil. And the word sanĭ, which is etymologically less clear, can be a shortened version of (due to de-tabooing) a taboo word sotona, satana 'adversary of God (= devil)'.