Principal English Translation: 

beneath, below, at the foot of (see Karttunen and Lockhart)

Frances Karttunen: 

-TZĪNTLAN compound postposition beneath / debajo de algo (C) See TZĪN-TLI, -TLAN.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 314.

Lockhart’s Nahuatl as Written: 

complex relational word. below, beneath. tzīntli, -tlan.
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), 240.

Attestations from sources in English: 

yn ocaxitique ytzintlan teucalli, in ie qujtlecauizque, ca nauhcampa ixticaca mecatl, injc cacoqujxtizque, ynjc qujnapalozque = When they brought it to the front of the temple, they carried up [the platform]. Cords fastened it to the four [corners], so that they might take it up, that they might carry it. (sixteenth century, Mexico City)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 2—The Ceremonies, No. 14, Part III, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1951), 70.