What is the origin/meaning of the word Purim? I always assumed it meant the multiple lots of Haman, but I just heard a shiur saying the word Purim comes from "pirurin" - little things - of the Megillah which we thank Hashem for.
Esther 9 (will edit in the exact verse, later) says explicitly:
"Therefore these days are called 'Purim' because of the 'Pur'".
It was named after the lots that Haman cast.
Anything else you see would be a Midrashic or supplemental interpretation to the above verse.
(Note that the term is in plural "these days". Implying that Purim can occur on one of several days. Gemarah Megillah delves into a lengthy discussion on this.)