a tributary, the meeting or merging of two rivers (see Molina)
Alonso de Molina:
icetca inome atoyatl. junta de dos rios. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 32r. col. 2. Thanks to Joe Campbell for providing the transcription.