a bearing wall, or a wall support (?) (see Molina)
Orthographic Variants:
tepan quachichiquilli
Alonso de Molina:
tepan quachichiquilli. cauallete de pared. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 102r. col. 2. Thanks to Joe Campbell for providing the transcription.