tetzahuitl.

See an image that represents tetzahuitl in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).

Injc, macuilli Capitulo, itechpa tlatoa, in oc centlamantli tetzavitl, in quichiuh naoalli titlacaoan = Fifth Chapter, which telleth of another fraud which the sorcerer Titlacauan wrought (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 3 -- The Origin of the Gods, Part IV, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1978), 17.

Ic chiquacen capitulo, vncan mjtoa in nez, in mottac, in machiotl, ioan in tetzaujtl, in aiamo oalhuj españoles in njcan tlalli ipan, ioan in aiamo iximachoia, in njcan chaneque. = Sixth Chapter, in which it is told how signs and omens appeared and were seen, when the Spaniards had not yet come to this land, and when they were yet unknown to the dwellers here. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 8 -- Kings and Lords, no. 14, Part IX, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1951), 17.

What in Spain they call agüero [omen] in Mexico they call tetzahuitl, though the Mexican word means a little more than the Castilian one, because it means "augury, omen, portent, or prodigy that foretells some present or future evil." All this is included in the word tetzahuitl. (Atenango, between Mexico City and Acapulco, 1629)
Hernando Ruiz de Alarcón, Treatise on the Heathen Superstitions That Today Live Among the Indians Native to This New Spain, 1629, eds. and transl. J. Richard Andrews and Ross Hassig (Norman and London: University of Oklahoma Press, 1984), 68.

Inic etetl tetzavitl: vitecoc ipan tlatlatzin teucalli = The third omen was that a temple was struck by lightning (central Mexico, sixteenth century)
James Lockhart, We People Here: Nahuatl Accounts of the Conquest of Mexico, Repertorium Columbianum v. 1 (Los Angeles: UCLA Center for Medieval and Renaissance Studies, 1993), 52.

in tetzavitl y temictli = the auguries, the dreams (central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 174.

ytetzauh mochiuh huey CoColistli = it was the omen of a great plague (Tlaxcala-Puebla, seventeenth century)
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), 94–95.

quin oncan quihualantiquizque in Diablo tetzahuitl Huitzilopochtli in huallaque ce cihuatl itoca Chimalma ompaqui hualhuicaque in Aztlan Chicocca hualquiztiaque inic hualnenenque. = después salieron de allá para acá asiendo al "diablo Tetzahuitl Huitzilopochtli"; cuando vinieron, trajeron de Aztlan Chicoccan a una mujer llamada Chimalma, cuando salieron y caminaron hacia aquí. [después de allá hacia acá salieron tomando al "diablo Tetzahuitl Huitzilopochtli"; cuando vinieron, de allá trajeron una mujer de nombre Chimalma, cuando vinieron a salir de Aztlan Chicoccan, cuando caminaron hacia acá.] (centro de Mexico, s. XVII)
Fernando Alvarado Tezozomoc, Crónica mexicayotl; traducción directa del náhuatl por Adrián León (México: Universidad Nacional Autónoma de México, 1998), 18.

"El tetzahuitl era un signo de la existencia de un desequilibrio que podía acarrear desgracias a las personas. Y aunque este vocablo pudo generar lecturas indígenas, muy distintas a las que pretendía el fraile, es probable que los autores lo hayan empleado para indicar que los religiosos que presenciaron los tormentos de la mujer aparecida, hicieron frente a un suceso extraordinario, concreción de una transgresión y al que los todos debían temer y tener por “agüero” para no correr con la misma suerte de la mujer pecadora."
Berenice Alcántara, "El dragón y la mazacóatl: Criaturas del infierno de un examplum en náhuatl de Fray Ioan Baptista," Estudios de cultura náhuatl no. 36 (2005, 388). Cita a Louise Burkhart.