a fat worm with horns, or a snake that does no harm (see Molina)
IPAspelling:
mɑsɑːkoːɑːtɬ
Alonso de Molina:
mazacoatl. gusano gordo con cuernos, o culebra grande que no haze mal. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 50r. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
MAZĀCŌĀ-TL pl: -MEH a type of horned cateroillar or a type of large, nonvenomous snake, a boa / gusano gordo con cuernos o culebra grande que no hace mal (M), culebra mazacuate (Z) [(2)Zp. 37, 166, (3)Xp. 52]. Several Spanish sources remark that the snake of this name is large enough to feed on four-legged animals. The literal sense of the name ‘deer snake’ probably refers to its alleged diet rather than to any aspect of its appearance. The caterpillar, on the other hand, takes its names from its antler-like projections. See MAZĀ-TL, CŌĀ-TL. Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 142.