xocoya.

Headword: 
xocoya.
Principal English Translation: 

to become acidic or sour (see Molina)

IPAspelling: 
ʃokoyɑ
Alonso de Molina: 

xocoya. ni. (pret. oxocoyac.) azedarse o auinagrarse.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 160v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

XOCOYA for something to sour, ferment, spoil / acedarse o avinagrarse (M), fermenta, agria, se echa a perder (comida) (T) [(1)Tp.247, (3)Zp.6,48,229]. See XOCOC.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 329–330.

Attestations from sources in English: 

xocoya (verb) = to become sour
Daniel Garrison Brinton, Ancient Nahuatl Poetry: Containing the Nahuatl Text of XXVII Ancient Mexican Poems (1877), 167.