the foundation of a building, already set up and made level, upon which a wall is constructed (see Molina)
Alonso de Molina:
tlatepechmantli. cimiento ya sacado e ygualado sobre el qual se edifica y comienza la pared. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 135v. col. 1. Thanks to Joe Campbell for providing the transcription.