In the Septuagint, the Greek translation of the Old Testament, Satan is usually referred to as diabolos or “slanderer” (from the Greek verb diaballein, “to slander,” literally “to throw across”). But in the Greek New Testament, the Hebrew word, which is Satanas or Satan in its Greek form, is used as if it were the devil’s proper name. The older Latin translations of the Bible retain Greek diabolos as diabolus, but St. Jerome’s version, the Vulgate, calls the devil Satan. Both words were borrowed into Old English, and we now call this figure both Satan and the Devil. The derived form devilish first appears in the 15th century.