an oven or stove made for sweating (similar to a sauna) (see Molina)
Alonso de Molina:
neitoniloyan. estufa para sudar, o cosa semejante. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 66r. col. 2. Thanks to Joe Campbell for providing the transcription.