something rare, such as almond milk (?) or the like (see Molina)
IPAspelling:
iːʃɑːtik
Alonso de Molina:
ixatic. cosa rala como almendrada, o cosa semejante. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 44v. col. 2. Thanks to Joe Campbell for providing the transcription.