omitl.

A document from Mexico City from the year 1600 that uses both matl and maitl for a measurement, speaking of chinampas, provides a window onto omitl: "matlactli oce mait ypan cemomitl." A translation from 1697 uses braza to translate matl/maitl, and explains that the omitl was 1/3 of a matl/maitl.
James Lockhart collection, notes in the file "Land and Economy." For this example he cites AGN (Mexico) Tierras, vol. 165, exp. 6, ff. 14v., 15r.

njman ic qujmontlapachoa, qujmonixqujmjloa, cecenme, ica neçaoalquachtli, tliltic omjcallo, ioan qujmonmaca icpaxiqujpilli, tliltic omjcallo, in vncan temj copalli = Then they veiled and covered their faces, each one of them, with black fasting capes designed with bones. And they gave them cotton incense bags, black and designed with bones, which they filled with incense (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 8 -- Kings and Lords, no. 14, Part IX, 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), 63.

omitl = a fraction of a matl, and it is translated as "codo," possibly making the measure from the elbow to the wrist (San Hipólito Teocaltitlan, Mexico City, 1592)
James Lockhart collection, notes in the file "Land and Economy." For this example he cites AGN Hospital de Jesús 298, no. 4, f. 3v, 12v.

"mitl" (short for omitl?) appears in a document and appears to be a fraction of a matl, translated twice as "media braza" (San Hipólito Teocaltitlan, Mexico City, 1593)
James Lockhart collection, notes in the file "Land and Economy." For this example he cites AGN Hospital de Jesús 298, no. 4, 14v.

nomiuh = my bone
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 92.

yn inecauhcatzin yn imomiyotzin Sanctome ompa = the relics and bones of saints (early seventeenth century, central New Spain)
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 26–27.

Bones (omitl) are given as some of the essential items found in the "devil's houses" (Sahagún).
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 116.

iyomiyo, yomiyo = his or her bones; omiyotl = bones
Robert Haskett and Stephanie Wood notes from Nahuatl classes with James Lockhart and subsequent research.

Uel nomiuh, uel momiuh. Itechpa mitoa: in tlein nicnopialia...no uel itech mocaquia in yeuecauh: in aquin tlamaya yaoc = Strictly my bone, strictly your bone. This is said when I hold fast to something that belongs to me...It meant the same in the past when someone took a captive in battle.
Thelma D. Sullivan, "Nahuatl Proverbs, Conundrums, and Metaphors, Collected by Sahagún," Estudios de Cultura Náhuatl 4 (1963), 106–107.

in nomiuh = your (sic?) bone (e.g. on your plate)
in nomiyo = your (sic?) bone (part of your body), your bones
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 99.

ça omitl aoctle ynacayo = sólo eran huesos descarnados (Tlaxcala, 1662–1692)
Juan Buenaventura Zapata y Mendoza, Historia cronológica de la Noble Ciudad de Tlaxcala, transcripción paleográfica, traducción, presentación y notas por Luis Reyes García y Andrea Martínez Baracs (Tlaxcala y México: Universidad Autónoma de Tlaxcala, Secretaría de Extensión Universitaria y Difusión Cultural, y Centro de Investigaciones y Estudios Superiores en Antropología Social, 1995), 402–403.

omitl = hueso; nomiuh (por no-omiuh) = mi hueso
Rémi Siméon, Diccionario de la lengua náhuatl o mexicana (Mexico: Siglo XXI, 1988), xliii.