the center; in the center of the land, or in the center of the Earth (see Molina)
Alonso de Molina:
tlalli olloco. centro, enel centro dela tierra. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 124r. col. 1. Thanks to Joe Campbell for providing the transcription.