a discourteous person, or someone who is foul-mouthed (see Molina)
IPAspelling:
ɑhtɬɑːkɑtɬɑhtoɑːni
Alonso de Molina:
atlacatlatoani. descortes o mal hablado. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 8r. col. 1. Thanks to Joe Campbell for providing the transcription.