tlalcualiztli.

Headword: 
tlalcualiztli.
Principal English Translation: 

eating earth (a ceremony); or, the act of taking an oath in a certain ceremony; kissing the earth; or putting earth in one's mouth
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan (Norman: University of Oklahoma Press, 1997), 71.

Orthographic Variants: 
tlalqualiztli
Alonso de Molina: 

tlalqualiztli. el acto de hazer juramento con cierta cerimonia. s. besando la tierra, o metiendola enla boca.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 124v. col. 1. Thanks to Joe Campbell for providing the transcription.