ehecacoatl.

Headword: 
ehecacoatl.
Principal English Translation: 

1) a type of snake, such as a constrictor or a pit viper (see Karttunen)
2) a tornado or a whirlwind (literally, wind-serpent) (see Karttunen and attestations)

IPAspelling: 
eheːkɑkoːɑːtɬ
Frances Karttunen: 

EHĒCACŌĀ–TL. There is disagreement about whether this is a constrictor or a pit viper. Sahagún and Clavijero both believe it is called a 'wind serpent' because of its swiftness, but it is also more directly associated with wind. M has the phrase eecacoayo mixtli 'storm cloud with whirlwind,' and T has EHQUETZALCŌĀ–TL 'whirlwind.'

Attestations from sources in English: 

tlatecihuiloc yuā quisaco ỹ eccacohuatl = it hailed and there were tornadoes
Here in This Year: Seventeenth-Century Nahuatl Annals of the Tlaxcala-Puebla Valley, ed. and transl. Camilla Townsend, with an essay by James Lockhart (Stanford: Stanford University Press, 2010), 174–175.

omochiuh chicahuac quiahuitl yhuan tesihuitl yca ehecacoatl = there was a great rainstorm with hail and a whirlwind.
Here in This Year: Seventeenth-Century Nahuatl Annals of the Tlaxcala-Puebla Valley, ed. and transl. Camilla Townsend, with an essay by James Lockhart (Stanford: Stanford University Press, 2010), 144–145.

Rey ypantera macoc = he was given the banner of the king [to parade about with]
Here in This Year: Seventeenth-Century Nahuatl Annals of the Tlaxcala-Puebla Valley, ed. and transl. Camilla Townsend, with an essay by James Lockhart (Stanford: Stanford University Press, 2010), 174–175.

See also: