mictlan.

Headword: 
mictlan.
Principal English Translation: 

place of the dead, land of the dead; hell, in hell, to hell (in colonial usage) (see Molina and Lockhart)

IPAspelling: 
miktɬɑːn
Alonso de Molina: 

mictlan. infierno, o enel infierno, o al infierno.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 56r. col. 2. Thanks to Joe Campbell for providing the transcription.

Lockhart’s Nahuatl as Written: 

mictlān. land of the dead, hell. some form of miqui or micqui and -tlān.
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), 225.

Attestations from sources in English: 

In the Florentine Codex (Book 6, Chapter 29) we learn that the women who died in war and in childbirth carried the sun on a litter of quetzal feathers to deliver it to Mictlan, into the hands of the Micteca. In Chapter 35 of this same book, we see references to the people the "lord destroyed and hid," the ancestors, whom he placed "in a coffer, in a reed chest" or sent off to be "in the water, in the cave, in the land of the dead" (in atlan, in oztoc, in mjctlan) (or: in atlan, in oztoc, in mictlan).

Cequintin momatque, ca mictlampa in quiçaquiuh, ic vmpa itztimomanque : cequintin cioatlampa: cequintin vitztlampa itztimomanque, nouiiampa motemachique: ipampa in çan tlaiaoalo tlatlauillotl. = Some thought that it would be from the north that [the sun] would come to rise, and placed themselves to look there; some [did so] to the west; some placed themselves to look south. They expected [that he might rise] in all directions, because the light was everywhere. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 7 -- The Sun, Moon, and Stars, and the Binding of the Venus, No. 14, Part VIII, 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), 6.

auh niman oualquizque in mictlan tequanime in tlatlacatecolo, oquimiztlacauique oquimtlapololtique oquinyoleuhque in tlalticpac tlaca inic tlateotocazque = and then the wild beasts of the place of the dead, the demons came out. They deceived, they confused, they inspired, they provoked the people of earth so that they would follow things as gods. (central Mexico, late sixteenth century)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 28.

amo çan quezquintin mictlan vi mictlan calaque mictlan motlaça = not just a few go to the place of the dead, enter the place of the dead, throw themselves into the place of the dead (late sixteenth century, central Mexico)
Louise M. Burkhart, Before Guadalupe: The Virgin Mary in Early Colonial Nahuatl Literature, Institute for Mesoamerican Studies Monograph 13 (Albany: University at Albany, 2001), 28.

in ChiucnāuhMictlān. In oncān nichuīcaz tlālli īnepantlah = to Nine-Mictlan. I will carry her there to the middle of the earth. (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), 80.

in īc ChiucnāuhMictlān yahqueh = they went to Nine-Mictlan [i.e., into a trance state] (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), 79.

aço teatlitiz, tetlamacaz, in topã in mjctlan, in jlvicac = Perhaps he will provide drink, will provide food above us, in the land of the dead, the heavens (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), 4.

The reference to Mictlan being "above us" and in the "heavens" (representing Christian influence or editing?) is echoed in: auh ca ie oalitztotoc ie oallachialotoc in topan in mictlan, in ilvicac in quezqui = And all those who are above us in Mictlan, in the sky, already lie watching, are already observing. (central Mexico, sixteenth century)
ernardino 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), 14.

ca mjctlan, ca ylujcac in otontemoc, in otontlachix = for thou hast descended into, thou hast beheld the land of the dead, the heavens (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), 32.

auh noce mjtzonmotlatiliz, mjtzõmocxipachilviz, mjtzonmjvaliz in tocenchan in mjctlan = And perhaps he will hide thee, put thee underfoot, send thee to our common home, the land of the dead (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), 33.

ca oqujnmotlatili in totecujo, â ca oqujnmotoptemjli, ca oqujnmopetlacaltemjli, ca oqujnmjhoali in atlan, in oztoc, in mjctlan = For our lord hath hidden them, hath placed them in a coffer, in a reed chest; he hath sent them in the water, in the cave, in the land of the dead (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), 195.

Attestations from sources in Spanish: 

yntlacamo melavac tiquitoz diablo mitzuicaz mictlan = si no dices la verdad el diablo te llevara al infierno (Tlaxcala, 1562)
Catálogo de documentos escritos en Náhuatl, siglo XVI, vol. I (México, Gobierno del Estado de Tlaxcala, 2013), 9–10.

ca yc tipoztequiz in tlalticpac ahnozo mictlan = así te quebrarás en la tierra o en la región de los muertos (México central, s. XVI)
Huehuehtlahtolli. Testimonios de la antigua palabra, ed. Librado Silva Galeana y un estudio introductorio por Miguel León-Portilla (México: Secretaría de Educación Pública, Fondo de Cultura Económica, 1991), 76–77.

...'lugar de los muertos,' nombre nahua del inframundo, se usaba en el sentido de 'infierno.' A los testigos de un juicio a los que se tomaba juramento de decir la verdad se les advertía ytla amistlactizque diablo mictlan amechtzacuiltiz: 'si mintieres, el diablo os castigará en el infierno.'
Al mismo tiempo que entraban a la lengua nahua palabras castellanas en préstamo, muchas palabras nahuas experimentaron una extensión de sentido para adecuarse a los cambios institucionales que experimentaba el pueblo. (Tlaxcala, s. XVI)
Thelma Sullivan, Documentos tlaxcaltecas del siglo XVI en lengua náhuatl (Mexico: Universidad Nacional Autónoma de México, 1987), 36.

Mictlan, ‘lugar de los muertos’, bocablo de muy frecuente empleo en la tradición prehispánica. Con él se quiso significar ‘infierno’. (Centro de Mexico, s. XVI)
Ascensión Hernández de León-Portilla, “Un Prologo en náhuatl suscrito por Bernardino de Sahagún y Alonso de Molina,” Estudios de Cultura Náhuatl 29 (1999), 199-208, example from page 207.

yn tlacamo mictlan quitzacuctiaz = sino será castigado en el infierno (Tlatelolco, 1573)
Luis Reyes García, Eustaquio Celestino Solís, Armando Valencia Ríos, et al, Documentos nauas de la Ciudad de México del siglo XVI (México: Centro de Investigación y Estudios Superiores en Antropología Social y Archivo General de la Nación, 1996), 85.

yhuan mictlan mapiluhuaya quitohuaya quitenehuaya cohuatl tamaçoli tlalticapac moquetzaya temachtiaya = Y señalaba con el dedo al infierno y decía: culebra, sapo. Parado sobre la tierra, enseñaba. (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), 98–99.