What is an "altatl" in mayan culture?

The word "atlatl" is actually of Nahua origin (that's another great culture of Pre-Columbian MesoAmerica)- and it's more typically a concept assotiated with the Aztecs.

Nonetheless, the Mayas used it too (the tool, not the word), and atlatl simply means a "spear"- it was a war tool, although most of the fighting was done in close-range, and not by throwing.