achtontli.

Headword: 
achtontli.
Principal English Translation: 

great-grandfather, ancestor (see Karttunen)

Orthographic Variants: 
achtōntli
IPAspelling: 
ɑtʃtoːntɬi
Alonso de Molina: 

achtontli. visabuelo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 2r. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

ACHTŌN-TLI great-grandfather, ancestor / bisabuelo (M) [(1)Bf.6v]. See ACHTO, ACHCŌL-LI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 3.

Lockhart’s Nahuatl as Written: 

achtōn-(tli) = great-grandfather
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 210.

Attestations from sources in English: 

Achtontli, aoc quimati ueue, oppa piltontli. = The Great-Grandfather [He is] decrepit, in his second childhood. (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), 5.

themes: 
Aging (People, Things)
Family, Kinship, Descent