zan nen.

Headword: 
zan nen.
Principal English Translation: 

in vain, just in vain; for nothing (see Molina and Carochi)

Orthographic Variants: 
zannen, çan nen
Alonso de Molina: 

zannen. en vano, o por demas. (aduerbio.)
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 14v. col. 1. Thanks to Joe Campbell for providing the transcription.

Horacio Carochi / English: 

çan nēn = in vain
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), 421–13, 499.