Principal English Translation: 

with, together with (...someone)

Alonso de Molina: 

Nouan. conmigo, o junatamente conmigo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, f. 74r.

Frances Karttunen: 

-HUĀN necessarily possessed form and, with / junto y en compañía de otro (C) T has lost the final N by general rule, and the vowel has shortened in word-final position. T and Z use HUĀN without a possessive prefix to mean ‘and,’ contrasting with ĪHUĀN ‘with him ~ her ~ it.’
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 81.

Horacio Carochi / English: 

nohuan = with me
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), 212 n2, 502.

Lockhart’s Nahuatl as Written: 

relational word. with, along with. 3rd person sing., ī-huān, and, in addition. 217
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), 217.

Attestations from sources in English: 

nohuan = with me
ihuan, yhuan = with him (easy to confuse with and)

See also: