The 3rd month in the Jewish calendar, which is May-June in the solar calendar.
Esther 8:9At that time the royal scribes were summoned on the twenty-third day of the third month, which is the month of Sivan. And an edict was written according to all that Mordecai commanded, and sent to the Jews and to the satraps, governors, and officials of the 127 provinces from India to Cush, to every province in its own script and to every people in their own language, and also to the Jews in their script and their language.