Principal English Translation: 

a staff with a crosspiece; a stick instrument, resting with the feet, and with the hands; or, the name of an instrument of one who works obsidian
All of these definitions come from A. Wimmer and the Gran Diccionario Náhuatl,, with translations here to English--as needed--by Stephanie Wood.

Attestations from sources in English: 

Various sources indicate that this was a tool for creating obsidian blades.
See, for example, Kenneth G. Hirth, Housework, 2010, p. 100.

Attestations from sources in Spanish: 

un bastón con gancho activo o Itzcolotli Javier Baena Preysler, Tecnología Lítica Experimental, 1998, p. 123.