the beginning, the start, the foundation of something (see Molina and Karttunen)
IPAspelling:
tsiːntilistɬi
Alonso de Molina:
tzintiliztli. principio, comienzo o fundamento de alguna cosa. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 152v. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
TZĪNTILIZ-TLI the beginning or foundation of something / principio, comienzo o fundamento de alguna cosa (M) [(2)Cf.75v]. See TZĪNTI, TZĪN-TLI. Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 314.