Atamalcualiztli.

Headword: 
Atamalcualiztli.
Principal English Translation: 

the Eating of the Water Tamales, an autonomous-era festival that was celebrated every eight years
Thelma D. Sullivan, "Tlatoani and Tlatocayotl in the Sahagún Manuscripts," Estudios de Cultura Náhuatl 14 (1980), 235.

Orthographic Variants: 
Atamalqualiztli
Attestations from sources in English: 

This was celebrated every eight years, and only tamales made with corn dough mixed with water were eaten. Thelma Sullivan says, "no condiments or other additives were permitted so as to give the corn a respite and a chance to regain its strength." (central Mexico, sixteenth century)
Thelma Sullivan, "Tlatoani and tlatocayotl in the Sahagún manuscripts," Estudios de Cultura Nahuatl 14 (1980), 225–238. See esp. p. 235.