ameyalco. manantial de agua o de fuentes. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 4v. col. 2. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
ĀMĒYALCO spring / manantial (T)[(1)Tp.170]. This is a locative meaning literally ´at the spring.´ See ĀMĒYAL-LI, -C(O). Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 10.