xixa.

Headword: 
xixa.
Principal English Translation: 

to urinate or defecate (see Karttunen and Molina)

IPAspelling: 
ʃiːʃɑ
Alonso de Molina: 

xixa. nino. (pret. oninoxix.) proueerse o hazer camara.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 159v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

XĪX(A) vrefl to urinate or defecate / proveerse o hacer cámara (M), cagar (M), orina (T) When this is compounded with Ā-TL ‘water,’ it still can mean to defecate as well as to urinate.

XĪXILIĀ applic. XĪX(A).

XĪXALŌ nonact. XĪX(A).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 327.