to fix one's cap so it will not fall; to pull back an arch string or crossbow with the thumb; or, to tie something with cords (see Molina)
IPAspelling:
mekɑjoːtiɑ
Alonso de Molina:
mecayotia. nitla. (pret. onitlamecayoti) poner fiador ala gorra, o cosa semejante, o empulgar arco, o ballestas o atar algo con cordeles. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 55r. col. 1. Thanks to Joe Campbell for providing the transcription.