huel.

Headword: 
huel.
Principal English Translation: 

well, very much so, greatly, really, truly, a lot; fine, good; definitely, surely, clearly, truly (see Molina and Lockhart); large

Orthographic Variants: 
vel, uel, huell, velh
Alonso de Molina: 

Vel. bien. Aduerbio.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, f. 156r.

Horacio Carochi / English: 

huel = intensifier and modal particle Horacio Carochi, S.J., Grammar of the Mexican language with an explanation of its adverbs (1645), translated and edited with commentary by James Lockhart, UCLA Latin American Studies Volume 89 (Stanford: Stanford University Press, UCLA Latin American Center Publications, 2001), 502.

Andrés de Olmos: 

Este algunas vezes esta en lugar de bene, y otras de possum. Ex. : uelh nicchiuaz, bien lo hare, o podre lo hazer.
Otras vezes esta en lugar de cierta o verdaderamente. Ex. : uelh oquichtli, cierto es hombre.
Andrés de Olmos, Arte para aprender la lengua Mexicana, ed. Rémi Siméon, facsimile edition ed. Miguel León-Portilla (Guadalajara: Edmundo Aviña Levy, 1972), 187.

Lockhart’s Nahuatl as Written: 

particle. very, greatly, fully, completely, general intensifier; sometimes well. also can indicate capability, possibility. reduced from hueli
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), 218.

Attestations from sources in English: 

vel necuitlaviloa vel ixpialoia = great care was taken to keep a good lookout (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), 140.

y ōca huell icha y vizilla = His real home is in Huitzillan.
(Cuernavaca, 1535–45)
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), 190.

ça àmō huel (also: za amo huel) = in no way

When an adverb, this is an intensifier that modifies other words around it.
Thelma Sullivan, Documentos Tlaxcaltecas del siglo XVI en lengua náhuatl (Mexico: Universidad Nacional Autónoma de México, 1987), 30.

Attestations from sources in Spanish: 

yn huel cuemitl quicui caxtol poalli ynon mecatipan = agarro un gran pedazo de tierra como trescientas brazas dos mecates (Tlaxcala, 1562)
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), 23.

ei persona ça ce huel neli yn Dios ça centeotl = tres personas distintas y un solo Dios verdadero
Vidas y bienes olvidados: Testamentos indígenas novohispanos, vol. 1, Testamentos en castellano del siglo XVI y en náhuatl y castellano de Ocotelulco de los siglos XVI y XVII, eds. Teresa Rojas Rabiela, Elsa Leticia Rea López, y Constantino Medina Lima (Mexico: CIESAS, 1999), 218–219.