Adar אדר

Haman's lot fell on Adar—and turned against him: Purim is kept on the fourteenth of Adar, and in cities walled since Joshua's days on the fifteenth, Shushan Purim. In leap years a second Adar is added, and Purim moves into it: thirteen months keep the lunar year in step with the sun, so that Nisan stays in spring. On the seventh of Adar, by tradition, Moses was born and died.

The month names now in use are Babylonian: "the names of the months came up with us from Babylon", says the Jerusalem Talmud. In the Torah months are counted—"the first", "the seventh"—from Nisan, the month of the Exodus.