-tech.

Headword: 
-tech.
Principal English Translation: 

next to

IPAspelling: 
-tetʃ
Alonso de Molina: 

Itech. en, enel, o del.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, f. 42r.

Notech. de mi, o en mi.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, f. 73v.

Frances Karttunen: 

-TECH postposition adjacent to, together with, adhering or attached to / junta con otra (C).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 216.

Horacio Carochi / English: 

-tech = next to (a general connector)
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), 512, and see 84-85, especially n4.

Lockhart’s Nahuatl as Written: 

relational word. joined to, next to; used as a general connector in verbal idioms with greatly varying translations depending on the verb.
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 232.

Attestations from sources in English: 

canel çenca huei, tetlaçotlaliztica, mopampa Cruztitech omomiquilli = since with very great love and charity He died for you on the cross
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 67.

Tetitech câ zoquitl = There's some mud on the rocks
Caltitech niczaloa āmatl = I'm gluing paper onto the house
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 122.

ytechoquiz, itechoquiz, ytech oquiz, itech oquiz = it emerged from;
notech = from me;
ytech = from him
Robert Haskett and Stephanie Wood's notes from Nahuatl sessions with James Lockhart and subsequent research.

iuhquin ma tetitech noneoa, nonnouitequi = It is as if I beat myself, I dash myself against a rock.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 108–109.

Often relates to being "on" or "touching" a vertical surface.
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 122.

Attestations from sources in Spanish: 

canel çenca huei, tetlaçotlaliztica, mopampa Cruztitech omomiquilli = pues quiso por el amor que nos tiene morir en vna Cruz
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 66–67.