matlactli once.

matlactli once.
Principal English Translation: 

eleven (see Molina); literally, ten plus one

Orthographic Variants: 
matlactli oce
Alonso de Molina: 

matlactli oce. onze.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 53r. col. 2. Thanks to Joe Campbell for providing the transcription.