to purchase two reales (two pieces of eight) worth of something
Orthographic Variants:
umetica xiccoa, ometica xiccoa
Alonso de Molina:
umetica xiccoa. compra dos reales de algo. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 158v. col. 2. Thanks to Joe Campbell for providing the transcription.