iyaya.

Headword: 
iyaya.
Principal English Translation: 

to stink, or stench (see Molina)

Orthographic Variants: 
îiaia, ŷiaia
IPAspelling: 
ihyɑːyɑ
Alonso de Molina: 

iyaya. n. (pret. oniyayac.) heder, o tener mal olor.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 36v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

(I)HYĀYA to stink / heder o tener mal olor (M) [(3)Tp.131,230,244 (7)Zp.12,34,54,66,227]. This drops the initial I after the reflexive prefixes but retains it after the nonspecific object prefix TLA-.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 102.

Attestations from sources in English: 

yiaxtiuh = it stinks; mjqujzîiaia (miquiziyaya) = it stinks of death (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), 132, 133.

îiaia = it stinks; ŷiaia = it stinks; cujtlâiac (cuitlayac) = smelling of excrement; mjqujciiac (miquiciyac) = smelling of death (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), 132.

xoqujiatic = fetid (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), 132.

themes: 
Sensory Perception (sound, smell, etc.)