huexiuhtli.

Headword: 
huexiuhtli.
Principal English Translation: 

father-in-law or mother-in-law of one's son or daughter (see Molina)

Orthographic Variants: 
uexiuhtli, vexiuhtli
Alonso de Molina: 

uexiuhtli. consuegro, o consuegra.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 157r. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

qujtoa, qujmjlvia in vexiuhti = he spoke to, he addressed those who had become in-laws (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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), 136.