to become hardened, to become obstinate (see Molina)
Orthographic Variants:
yollotepitztlaquactia
Alonso de Molina:
yollotepitztlaquactia. ni. (pret. oniyollo tepitztlaquactiac.) endurecerse y obstinarse. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 40v. col. 1. Thanks to Joe Campbell for providing the transcription.