to protect or shelter from the rain, or to hide (see Molina)
Alonso de Molina:
iyyana. nin. (pret. oniniyan.) guarecerse dela lluuia, o esconderse. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 36v. col. 2. Thanks to Joe Campbell for providing the transcription.