cacaxtli.

Headword: 
cacaxtli.
Principal English Translation: 

a carrying frame fitted to the human back
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), 212.

could be used for carrying birds (see Molina), and it can be part of a metaphor for governance when paired with quimilli (see attestations)

IPAspelling: 
kɑːkɑːʃtɬi
Alonso de Molina: 

cacaxtli. escalerillas de tablas para lleuar algo acuestas el tameme, o cierto paxaro.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 10v. col. 2. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

CĀCĀX-TLI, pack frame / escalerillas de tablas para llevar algo a cuestas el tameme (M) [(5)Bf.5r,5v,7r].
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 19.

Attestations from sources in English: 

"...a device of bound slats used to carry heavy loads."
Caciques and their People: A Volume in Honor of Ronald Spores (1994), 131.

"merchant's pack" and "backpack"
Venus-regulated Warfare and Ritual Sacrifice in Mesoamerica: Teotihuacan and the Cacaxtla "Star Wars" Connection (1991), 88, 47.

In the Florentine Codex (e.g. Book 6, Chapter 34) we see bundle and carrying frame used as a metaphor in association with the rulers' job of governing. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, ˆ, No. 14, Part 7, 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, 1961), chapter 34, 184.

In tlacaquimilli, in tlacacacaxtli, oitlan tonac otoconmama. Inin tlatolli, itechpa mitoaya: in aquin tlatocatlalili, azo tecuteco. = A bale of people, a cargo of people, you have taken upon you and loaded on your back. This phrase was said of someone who had been instated as king and ruler.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 172–173.

auh in oconquetzteoaque in vei qujmjlli, in vei cacaxtli, in vei tlamamalli, in tlatconj = They departed leaving the large bundle, the large carrying frame, the great burden, the subjects (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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, 1961), 22.

tehoatl itlan tonaquj in vei qujmilli, in vei cacaxtli, in tlatconj, in tlamamalonj = Thou art to devote thyself to the great bundle, the great carrying frame, the governed (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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, 1961), 48.

ma ximuchichioa ma itlan xaquj in qujmjlli, in cacaxtli = prepare thyself, put thy shoulder to the bundle, to the carrying frame (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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, 1961), 49.

tehoatl tiqujnqujmilpatlaz, tiqujncacaxpatlaz in totecujiooan in tetecutin, in tlatoque, in ie nachca onmantivi = Thou wilt assume the bundle, assume the carrying frame for our lords, the noblemen, the rulers who remain residing beyond (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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, 1961), 184.

tiqujmjle, ticacaxe tiez, tehoatl timalacaioaz, tehoatl tecauhiooaz, ticeoalloaz: motlan mocalaqujz in cujtlapilli, in atlapalli = thou art to be the one with the bundle, the carrying frame. Thou art to be the umbrage, thou art to be the shade, the shadow, beneath which the vassals are to enter (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, 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, 1961), 184.

Attestations from sources in Spanish: 

"instrumento para cargar"
XXXV Congreso Internacional de Americanistas, Actas y memorias, vol. 1 (1964), 442.

"armazón para cargar"
Latin American Indian Literatures Journal 20:2 (2004), 184.

A ca uncan, in oconcauhtehuac, oconquetztehuac in quimilli, in cacaxtli, in tlatconi, in tlamamaloni = Pues es verdad que al irse allá, dejó, detuvo el quimilli, el cacaxtli, el tlatconi, el tlamamaloni
Estudios de cultura náhuatl, 13–14 (1978), pp. 72–73.

"Que cosa y cosa, que tiene las costillas de fuera y esta llevantado [sic] en el camjno. es el cacaxtli" = "what is that which has the ribs on the outside and stands on the road? It is the cacaxtli." (central Mexico, sixteenth century)
Quoting Sahagún. Victoria Ríos Castaño, "Translation purposes in Sahagún's Libro de la Rethorica," en Otto Swartjes, Klaus Zimmerman, y Martina Schrader-Kniffki, eds., Missionary Linguistics V / Lingüística Misionera V (2012), 77.

themes: 
Animals, Bugs, Insects, Reptiles, Fish, etc.
Markets, Commerce, Economy
Technology, Tools