Why is the holiday named "Purim"?

"Haman sought to annihilate all the Jews, Mordechai's people, throughout Ahasuerus' entire kingdom. In the first month, which is the month of Nissan, in the twelfth year of King Ahasuerus' reign, a pur, which is a lot, was cast before Haman, for every day and every month, [and it fell] on the twelfth month, which is the month of Adar" – Book of Esther 3:6-7.

"For Haman, son of Hamdatha, the Agagite, persecutor of all the Jews, plotted against the Jews to destroy them, and he cast a pur, which is a lot, to shatter them and destroy them ... For this did they call these days "Purim," after the pur..." – ibid. 9:24, 26.

Haman drew lots to determine the day when to schedule the extermination of the Jews.

Why is this seemingly trivial detail of Haman's plot magnified to the extent that the holiday is named after it? And why is the holiday given a name drawn from the Persian language?

See:

A Throw Of Dice

The Pur of Purim

The Illogical Holiday

Best wishes and Shabbat Shalom,

Chani Benjaminson,
Chabad.org