a measure, a gauge, a standard (see Karttunen and Molina); also, a half fanega, or a "celemin" (which was 4.5 liters, but that seems small to Víctor Castillo)
Víctor M. Castillo F., "Unidades nahuas de medida," Estudios de Cultura Náhuatl 10 (1972), 195–223, see p. 207.