to lather with soap (see Molina)
amollalia. nitla. (pret. onitlaamollali.) enxabonar algo. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 5r. col. 2. Thanks to Joe Campbell for providing the transcription.