ni.san is the proper name of a month, used to date events in royal settings.

The attested use is a proper month name marking the time of events: Esther 3:7 dates the casting of Purim's lot, and Nehemiah 2:1 dates the presentation of wine before the king.

1. Month name in event dating · dominant

   Both occurrences are tagged Noun · Proper and place the form within a dating clause. In Esther 3:7 the APB renders “the first month, the month of Nisan” as the setting for the lot cast before Haman; in Nehemiah 2:1 it renders “the month of Nisan” as the time when wine was before the king.

   Esther 3:7Nehemiah 2:1

In the Anselm Project Bible: The APB explicitly presents the term as “the month of Nisan” in both Esther 3:7 and Nehemiah 2:1; in Esther 3:7 it also calls it “the first month.” The verse is read as a whole.