ipan nihualtemo in cahuallo.

(a loanword from Spanish)

ipan nihualtemo in cahuallo.
Principal English Translation: 

to dismount (see Molina)
(contains a Nahuatlized loanword from Spanish: caballo, horse)

Orthographic Variants: 
ipan niualtemo yn cauallo
Alonso de Molina: 

ipan niualtemo yn cauallo (pret. ipan oniualtemoc yn cauallo.) apearse.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 41v. col. 2. Thanks to Joe Campbell for providing the transcription.