The word in the Hebrew Bible that we translate as “leprosy” is tsara‘ath. It has been translated as “leprosy” only because of a linguistic blooper. In fact, tsara‘ath includes a wide variety of skin conditions.

When the Hebrew Bible was translated into Greek (the Septuagint), the Greek word lepra was used for tsara‘ath. Like tsara‘ath, lepra was then a rather vague term indicating a variety of skin conditions and diseases. Interestingly, the Greeks had a term for true leprosy—elephantiasis Graecorum—but the Septuagint translators did not use that term. Instead they use the more generic term lepra, accurately reflecting the meaning of tsara‘ath.

New Testament writers who read their Scriptures in the Septuagint version naturally used lepra to include a variety of skin diseases.

When the Bible was translated into Latin, lepra was simply written in Latin letters since the Latin language had adopted the Greek term lepra. So far, so good. The term was imprecise in both Greek and Latin, just as the Hebrew tsara‘ath was.

Confusion entered, however, in the course of the development of medieval medical terms. The medieval physicians of Europe learned their medicine largely from Arabic medical texts. As previously noted, the Greek term for leprosy was elephantiasis Graecorum. Since the Arabs already had a disease that used an elephant term, they translated elephantiasis Graecorum as juzam. When this term was translated into Latin for medical purposes in the Middle Ages, the word lepra was used. Thus lepra now had a specific medical meaning—what we know as leprosy. And of course that became the name of the disease English. But in Scripture, lepra was a vague term for a variety of skin diseases. Although leprosy is now a specific disease, both medically and in popular usage, in English Bible translations it is not.