something unnecessary, illicit, and without benefit (see Molina)
Alonso de Molina:
aneconi. cosa no necessaria, ylicita y sin prouecho. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 6r. col. 1. Thanks to Joe Campbell for providing the transcription.