Principal English Translation:
a vow, a promise, a vote (see Karttunen and Molina)
Alonso de Molina:
netolli. voto.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 71r. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
NEHTŌL-LI vow, promise, vote / voto (M) [(1)Rp.112]. By general derivational rules the vowel of the second syllable should be long, but it is unmarked for length in R. In derived NEHTŌLTIĀ T has the reflex of a long vowel. See (I)HTOĀ.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 163.
Attestations from sources in English:
netolle = one who makes a vow
Robert Haskett and Stephanie Wood's notes from Nahuatl sessions with James Lockhart and subsequent research.
caxilti yn inehtol = she fulfilled her vow (early seventeenth century, Central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 146.
Attestations from sources in Spanish:
nimoneltoltiya nicceliya juramento = he hecho juramento (Tlaxcala, 1567)
Catálogo de documentos escritos en náhuatl, siglo XVI, vol. I (Tlaxcala: Gobierno del Estado de Tlaxcala y el Archivo Histórico del Estado de Tlaxcala, 2013), 74.