a blunt spike of wheat, or the like (see Molina)
otzontepeuac. espiga de trigo mocha, o cosa semejante. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 78r. col. 2. Thanks to Joe Campbell for providing the transcription.