zan iyo.

Headword: 
zan iyo.
Principal English Translation: 

only; alone; or, just this one (an adverb)

Orthographic Variants: 
çaniyahu, zanio, zaniyo, çaniyo, çan iyo
Alonso de Molina: 

çaniyo. solamente, o solo. aduerbio. o solo este, esta, o esto.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, f. 14r.

zaniyo. solamente, o solo. aduerbio. o solo este. esta, o esto.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 14r. col. 2. Thanks to Joe Campbell for providing the transcription.

zanio. lo mesmo es que zaniyo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 14r. col. 2. Thanks to Joe Campbell for providing the transcription.

Lockhart’s Nahuatl as Written: 

çaniyoh, usually particle. only (exclusively). can also function as an indefinite pronoun with abs. pl. çaniyohqueh. çan, iyoh (alone)
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), 213.