tzintlantli. nalga. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 152v. col. 2. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
TZĪNTLAN-TLI buttocks, base / nalga (M), su nalga, su cadera, sus asentaderas, su cimiento (Z) [(5)Zp.15,23,28,88,162]. See –TZĪNTLAN. Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 314.