zan achica.

Headword: 
zan achica.
Principal English Translation: 

often; or, frequently (an adverb) (see Molina)

Orthographic Variants: 
çan achica
Alonso de Molina: 

zan achica. amenudo, o frequentemente. (aduerbio.)
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 14r. col. 1. Thanks to Joe Campbell for providing the transcription.