Principal English Translation:
gray, ashen, brown (see Molina and Karttunen)
Alonso de Molina:
nextic. cosa parda o de color de ceniza.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 71v. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
NEXTIC something gray, ashen / gris, de color ceniciento (S), gris, pardo, color de plomo (T) See NEX-TLI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 171.
Attestations from sources in English:
nextic = ashen (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, 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, 1961), 95.
Attestations from sources in Spanish:
Nextic = Pardo
Antonio Vázquez Gastelu, Arte de lengua mexicana (Puebla de los Angeles, México: Imprenta Nueva de Diego Fernández de León, 1689), 32r.