Pur
"Pur" is the Persian-loan word the text glosses for the reader as "the lot." The single occurrence sits in the throne-room scene of Esther 3, where Haman fixes the date for his planned destruction of the Jews by casting lots.
The Lot Cast Before Haman
The text introduces the term with its gloss in the same clause: "In the first month, which is the month Nisan, in the twelfth year of King Ahasuerus, they cast Pur, that is, the lot, before Haman from day to day, and from month to month, [to] the twelfth [month], which is the month Adar" (Es 3:7).
The casting fixes a calendar interval — from Nisan, the first month, to Adar, the twelfth — and supplies the name later attached to the festival commemorating the deliverance from Haman's plan. The lot is the hinge on which the date of the threatened day is decided; the festival of Purim takes its name from this same word.