a rudeness of understanding or of wit or ingenuity (see Molina); literally, "heart-death"
Alonso de Molina:
yollo miquiliztli. rudeza de entendimiento o de ingenio. 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.