tzontecomatl.

Headword: 
tzontecomatl.
Principal English Translation: 

head, skull; head of cattle; the human head cut off and separated from the body (see Molina)

IPAspelling: 
tsontekomɑtɬ
Alonso de Molina: 

tzontecomatl. cabeza cortada y apartada del cuerpo.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 153v. col. 1. Thanks to Joe Campbell for providing the transcription.

Frances Karttunen: 

TZONTECOM(A)-TL pl: -MEH; possessed form: -TECON head, skull / cabeza cortada y apartada del cuerpo (M), cabeza (C), cráneo (T) Z has an idiosyncratic possessed form -TZONTECOMAT where the absolutive suffix appears to be present. Z also has another possessed form ending in -TECŌN, where the absolutive is not /317/ present, but the long vowel of the final syllable makes it appear to be derived from CŌM(I)-TL rather than COM(A)-TL. See TZON-TLI, TECOM(A)-TL, CŌM(I)-TL.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 318.

Lockhart’s Nahuatl as Written: 

tzontli, tecomatl.
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: 

in ipan mihotia cecentetl in tzontecomatl = each one danced with the heads [of the captives] (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), 85.

tzontecomatl = severed heads; literally, hair pots, hair gourds; tzontecomatlan = next to the severed heads (toponym) (central Mexico, sixteenth century)
Angel Julián García Zambrano, "Ancestral Rituals of Landscape Exploration and Appropriation among Indigenous Communities in Early Colonial Mexico," in Sacred Gardens and Landscapes: Ritual and Agency, ed. Michel Conan (Washington, D.C.: Dumbarton Oaks Research Library and Collection, Harvard University Press, 2007), 199.

Ācuetzpal chimalli nauhcompa tzontecome = lizard-shield that has four heads (Atenango, between Mexico City and Acapulco, 1629)
Hernando Ruiz de Alarcón, Treatise on the Heathen Superstitions That Today Live Among the Indians Native to This New Spain, 1629, eds. and transl. J. Richard Andrews and Ross Hassig (Norman and London: University of Oklahoma Press, 1984), 58.

onimichmictic onicpopoztequi mobara ca yhuan mochi motzontecon nictlapanaz = Yes, I beat you and splintered your staff, and I will break your whole head. (Jalostotitlan, 1611)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 27, 166–167.

quinquaquauhço in intzontecon in Españoles: no quiçoçoque in cavallosme intzōtecon = they strung the Spaniards' heads on poles [on the skull rack]; they also strung up the horses' heads (central Mexico, sixteenth century)
James Lockhart, We People Here: Nahuatl Accounts of the Conquest of Mexico, Repertorium Columbianum v. 1 (Los Angeles: UCLA Center for Medieval and Renaissance Studies, 1993), 216.

ca much vncā [fol.31] icuiliuhtoc in tzontecomatl, nacaztli, iollotli, cuitlaxculli eltapachtli, tochichi, macpalli, xocpalli = for there were painted all severed heads, ears, hearts, entrails, livers, lungs, hands and feet (central Mexico, sixteenth century)
James Lockhart, We People Here: Nahuatl Accounts of the Conquest of Mexico, Repertorium Columbianum v. 1 (Los Angeles: UCLA Center for Medieval and Renaissance Studies, 1993), 128.

yvan centetl coyotl ytzontecon yuan patzactli çanno yuh mopiyaz = and a coyote's head (headdress) with crest device will also be so kept (Tlaxcala, 1566)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 1, 50–51

tzontecomatl = head -- used as synonymous with ilhuicatl (heaven), and this link is especially manifest in the belief that the hair from the top of the head contained tonalli, or the celestial life force, a spiritual component of different beings associated with their destiny (central Mexico, sixteenth century)
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), 106.

Karttunen writes: "Z[acapoaxtla] also has another possessed form ending in -TECŌN, where the absolutive is not present but the long vowel of the final syllable makes it appear to be derived from CŌM(I)-TL (cōmitl) rather than COM(A)-TL (comatl)."
Harold Key and Mary Ritchie de Key, Vocabulario de la Sierra de Zacapoaxtla, Puebla (Mexico City: Summer Institute of Linguistics, 1953)

tzontecomatl = county seat (central Mexico, late seventeenth or early eighteenth century)
Byron McAfee translation of the Tepotzotlan Techialoyan, published in Donald Robertson, The Techialoyan Codex of Tepotztotlan: Codex X (Rylands Mexican Ms. 1), Bulletin of the John Rylands Library 43:1 (Sept. 1960), 127.

tzontecotliltlacuilolli = cabecera document (central Mexico, late seventeenth or early eighteenth century)
Stephanie Wood, Mapa de Tolcayuca f. 3r., The Mapas Project, University of Oregon; write [email protected] for access to web pages. James Lockhart assisted with the translation.

çan ixquich yn cohuatzontecomatl oncan neztica nenepillotoc yn cohuatl tlatlauhqui = a sperpent’s head, from which the tongue is seen to extend; the serpent is red. (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 2, 22–23.

auh in itzontecon onpa oquitlalito yn canpa otemictique = They went to place his head where they had killed people. (Tlaxcala/Puebla, seventeenth century)
Here in This Year: Seventeenth-Century Nahuatl Annals of the Tlaxcala-Puebla Valley, ed. and transl. Camilla Townsend, with an essay by James Lockhart (Stanford: Stanford University Press, 2010), 140–141.

totzõteco toquavivixooa = Our head: We shake our head (central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 255.

Nechcocoa notzontecon huan axnicnequi nimehuaz. = "My head hurts and I donʻt want to get up." (La Huasteca, twenty-first century)
An idiezac posting on Twitter, June 2010.

See also tzontecomac tlacuilolli.

Attestations from sources in Spanish: 

oticto ixpantililique yn tlamatl, maba ihuan isontecomac tla quiloli = le presentamos a él, el papel de las tierras que se llama mapa y también la pintura principal (Estado de Hidalgo, ca. 1722?)
Rocío Cortés, El "nahuatlato Alvarado" y el Tlalamatl Huauhquilpan: Mecanismos de la memoria colectiva de una comunidad indígena (New York: Hispanic Seminary of Medieval Studies, Colonial Spanish American Series, 2011), 31, 43.

centzontli yhuan zenpoali onmactlactli tzontecomatl bacas toros becerros be[ce]rras gueguey yhuan tepitzitzin = cuatrocientas y treinta cabezas de ganado mayor, vacas, toros, becerras y becerros grande y chico (Tepexi de la Seda, 1621)
Vidas y bienes olvidados: Testamentos en náhuatl y castellano del siglo XVII, vol. 3, Teresa Rojas Rabiela, et al, eds. (México: CIESAS, 2002), 110–111.

Ytzonteco ypeuhca yn testamento = Cabeza y principio deste testamento (Tulancingo, México, 1577)
Vidas y bienes olvidados: Testamentos indígenas novohispanos, vol. 2, Testamentos en náhuatl y castellano del siglo XVI, eds., Teresa Rojas Rabiela, Elsa Leticia Rea López, Constantino Medina Lima (Mexico: Consejo Nacional de Ciencias Tecnología, 1999), 184–185.