nacochtli.

Headword: 
nacochtli.
Principal English Translation: 

ear plugs (more prestigious) or ear flares (less prestigious)
Justyna Olko, Turquoise Diadems and Staffs of Office: Elite Costume and Insignia of Power in Aztec and Early Colonial Mexico (Warsaw: Polish Society for Latin American Studies and Centre for Studies on the Classical Tradition, University of Warsaw, 2005), 162.

Orthographic Variants: 
nacuchtli
Alonso de Molina: 

nacochtli. orejeras.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 062v. col. 1. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

nacochtli = an ear plug
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), 57.

teocuitlanacochtli = golden earplugs (especially prestigious);
xiuhnacochtli = turquoise earplugs (equally prestigious);
mayananacochtli = green june beetle earplugs;
itznacochtli = obsidian earplugs (more common, less prestigious);
cuetlaxnacochtli = leather earplugs (awarded to warriors of the higher ranks);
quetzalcoyolnacochtli = curved green ear pendants with bells (given to pochteca who participated in a conquest)
Justyna Olko, Turquoise Diadems and Staffs of Office: Elite Costume and Insignia of Power in Aztec and Early Colonial Mexico (Warsaw: Polish Society for Latin American Studies and Centre for Studies on the Classical Tradition, University of Warsaw, 2005), 162, 164, 166, 167.

yteucujtlanacoch = her golden ear plugs (central Mexico, sixteenth century)
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), 83.

yxiuhtotonacuch = her ear plugs of lovely cotinga feathers
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 103.

chalchiuhteponaztli, nacatica cuitlalpitoc... tla ca nenca nacochtli. = a two-tone drum of jade ringed with flesh?...it is an ear-plug.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 130–131.

in tetepeiotl, in xivitzolli, in matemecatl, in cotzeoatl, in nacochtli, in tentetl, in tlalpilonj = the peaked cap, the turquoise diadem, the arm band, the band for the calf of the leg, the ear plug, the lip rod, the head band (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), 57.

Ҫaҫan tleino chalchiuhtepunaztli, nacatica cujtlalpitoc. Aca qujttaz toҫaҫanjltzin, tlacanenca nacochtli = What is it that is a horizontal drum of green stone bound about the middle with flesh? One can see from our little riddle that it is the ear plug (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), 237.

auh ticvecapanoa in tetepeiotl, in xivitzolli, in matemecatl, in cotzeoatl, in nacochtli, in tentetl, in tlalpilonj (“now you lift, you aggrandize the rule, the rulership: you raise the peaked headdress, the pointed turquoise thing [diadem], the arm band, the leg band, the earplug, the labret, the hair binder") (citing the Florentine Codex, Book VI) (sixteenth century, central Mexico)
Justyna Olko, Insignia of Rank in the Nahua World (2014), 372.

Attestations from sources in Spanish: 

Ҫaҫan tleino chalchiuhtepunaztli, nacatica cujtlalpitoc. Aca qujttaz toҫaҫanjltzin, tlacanenca nacochtli = Que cosa y cosa, vn teponaztli hecho de vna piedra preciosa y ceñjdo con carne biua. Es la orejera hecha de piedra preciosa que esta metida en la oreja (centro de Mexico, s. XVI)
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), 237.