chahua.

CHĀHU(A) someone in an irregular, nonlegitimate relationship, someone likely to arouse jealousy, mistress / mi combleza (M for possessed form) S gives chauatl, but since this only appears in compounds and in possessed form, the absolutive suffix is unattested. T has the pejorative diminutive CHĀHUATŌN. M has compounds of CHĀHU(A) with COCOY(A) ‘for a woman to be miserable on account of her husband's mistress, or to be gravely ill,’ with NECOCOY(A) ‘to be possessed by evil,’ with CONĒ-TL and PIL-LI ‘stepchild,’ and with NĀN-TLI ‘stepmother.’ See CHĀHUATI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 45.