What does "Pur," the word behind the name Purim, mean?

Answer: The lot

Haman cast the Pur (that is, the lot) to choose the day to destroy the Jews; the festival of Purim takes its name from it.

“In the twelfth year of King Xerxes, in the first month, the month of Nisan, the Pur (that is, the lot) was cast before Haman to determine a day and month. And the lot fell on the twelfth month, the month of Adar.”— Esther 3:7 (BSB)