cuilchilli.

Principal English Translation: 

the anus (see Sahagún)

IPAspelling: 
kwiltʃilli
Alonso de Molina: 

cuilchilli. el saluonor.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 26v. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

cuilchilli = anus
mimiltic = cylindrical
chichiltic = chili-red
celic = tender
iamaztic = soft
chichiliui = it becomes chili-red
celia = it becomes tender
cuilchilquiҫa = it has hemorrhoids
cuilchiltentli = edge of anus
tilaoac = thick (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 123.

themes: 
Anatomy