conjunction of the moon (literally, the moon's death) (see Molina)
Alonso de Molina:
metztli imiquiz. conjunction de luna. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 55v. col. 1. Thanks to Joe Campbell for providing the transcription.