Principal English Translation: 

at the edge, side, next to

Frances Karttunen: 

-TĒNCO compound postposition at the edge of something / su orilla (T for third pers. sg. possessor) See TĒN-TLI, -C(O).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 224.

Attestations from sources in English: 

ohtenco = at the edge of the road