tecolli.

Headword: 
tecolli.
Principal English Translation: 

charcoal (see Molina and Karttunen)

Orthographic Variants: 
teculla
IPAspelling: 
tekolli
Alonso de Molina: 

tecolli. carbon.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 93r. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

TECOL-LI pl: -TIN charcoal / carbón (M) [(l)Tp.224,(2)Zp.25,219,(3)Xp.83].
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 216.

Attestations from sources in English: 

chipaoac atl, in quauitl, in tlatlatilquauitl, in tecolli, in apaztli, in petzcaxitl, in apilloli, in tzotzocolli in tlatzoionilcaxitl, in ic ixquich in çoquitlatquitl = fresh water, wood, firewood, charcoal, earthen tubs, polished bowls, water jars, large clay pitchers, vessels for frying, all kinds of earthenware. (Mexico City, sixteenth century)
James Lockhart, We People Here: Nahuatl Accounts of the Conquest of Mexico, Repertorium Columbianum v. 1 (Los Angeles: UCLA Center for Medieval and Renaissance Studies, 1993), 122.

ca ic nezcolo, ic tlapaoaxo, ic tlacuxitilo, ic tlaxco, ic iztatlatilo, ic necutlatilo, ic tecullatilo, ic tenextlatilo = for {with fire, thus} one was warmed, things were cooked on a plate, things were cooked in a pot, pottery was fired, salt was burned, syrup was boiled, charcoal was burned, the lime was burned (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 1 -- The Gods; No. 14, Part 2, 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, 1950), 11.