Principal English Translation:
for something to break, bust open, snap, break in two, such as a rope, thread, etc.; to be broken off (see Molina, Karttunen, and Lockhart)
Alonso de Molina:
cotoni. (pret. ocoton.) quebrarse la cuerda o el hilo soga. &c.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 24v. col. 2. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
COTŌN(I) for a cord, thread, or rope to snap / quebrarse la cuerda o el hilo, soga, etc. (M). See COTŌN(A).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 42.
Lockhart’s Nahuatl as Written:
ni. to be broken off, cut. Class 2: ōnicotōn. intransitive equivalent of cotōna.
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), 216.
Attestations from sources in English:
acan cotonj, acan momacaoa vipantiuj = at no time breaking the line [of dancers], at no time losing hands, they went in orderly procession
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), 102.
cotōni = to snap, be cut off (colonial Mexico)
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 197.
IDIEZ def. náhuatl:
Tlamahcahua cuamecatl, lazoh zo iloh tlen tlahuel motilantoc. "Ne cuahuizolli nochi cotonqui pampa axquimalhuihqueh conemeh quemman mohuizoyaya. "
IDIEZ def. español:
A. Se hace pedazos el mecate, una cuerda o hilo lo que se gala mucho y no aguanta. “Ese columpio se reventó todo porque no lo cuidaron los niños cuando se mecian”.
B. Se revienta algo.