Principal English Translation: 

as, like, similar to a (fill in the blank)

Frances Karttunen: 

-TEUH. in the manner of / a manera de (C) [(2)Cf.18v]. This is a necessarily bound form.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 237.

Horacio Carochi / English: 

-teuh = like
Horacio Carochi, S.J., Grammar of the Mexican language with an explanation of its adverbs (1645), translated and edited with commentary by James Lockhart, UCLA Latin American Studies Volume 89 (Stanford: Stanford University Press, UCLA Latin American Center Publications, 2001), 513, and see 78-81.

Attestations from sources in English: 

quetzalteuh = like a quetzal feather
Robert Haskett and Stephanie Wood's notes from Nahuatl lessons with James Lockhart and subsequent research.