Athbash

A Hebrew cryptograph, a secret writing system used to hide messages.

The first letter of the Hebrew alphabet is replaced by the last letter.

The second letter is replaced by the next-to-last letter.

This pattern continues for all letters.

This secret writing system was used in Jeremiah 51:1 for the word “Chaldea." It was also used in Jeremiah 25:26 and 51:41 for the word “Babylon” (written as “Sheshach.”)

The Septuagint, the early Greek translation of the Old Testament, correctly translated these codes as “Chaldea” and “Babylon” respectively.