Principal English Translation:
the name of a month of twenty days
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), 174. 178.
Attestations from sources in English:
"During the month of Panquetzaliztli, which did honor to Huitzilopochtli, the merchants were charged with the sacrificing of bathed slaves." They would enter the sand after being sacrificed. (sixteenth century, central Mexico)
Charles E. Dibble, "The Xalaquia Ceremony," Estudios de Cultura Nahuatl 14 (1980), 197–202, see especially 199–200.
Attestations from sources in Spanish:
Panquetzaliztli = "'Levantamiento de banderas' o funcionar como el numeral 'veinte' y como signo fonético del sonido 'pan', así como indicar metonímicamente el sacrificio humano." (p. 85)
Katarzyna Mikulska, "Te hago bandera... Signos de banderas y sus significados en la expresión gráfica nahua", en Los códices mesoamericanos: registros de religión, política y sociedad, Miguel Ángel Ruz Barrio y Juan José Batalla Rosado, coordinadores (Zinacantepec: El Colegio Mexiquense, 2016), 85–133.