from the other part of the river or lake (see Molina)
Orthographic Variants:
ateputzco
Alonso de Molina:
ateputzco. dela otra parte de rio, o de la laguna. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 7v. col. 2. Thanks to Joe Campbell for providing the transcription.