Mexico.

Headword: 
Mexico.
Principal English Translation: 

a place name, the altepetl of the Mexica, Mexico Tenochtitlan, or Mexico City as it was considered by the Spaniards -- sometimes considered to include Tlatelolco, also inhabited by Mexica
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.

IPAspelling: 
meːʃihko
Frances Karttunen: 

MĒXIHCO Mexico / México (C)[(4)Bf.2r,9V, LLr, (4)Cf.56r, 79r, 102r, Io4r, (I)Tp.142]. The etymology of this is opaque. Because of the difference in vowel length, it cannot be derived from ME-TL ‘maguey.’ the sequence XIH also differs in vowel length from XĪC-TLI ‘navel,’ which has been proposed as a component element. The final element is locative –C(O).
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 145.

Attestations from sources in English: 

"In Chimalpahin 'Mexico' still has the traditional Nahuatl meaning of the area inhabited by the Mexica in the narrower ethnic sense, limited to Tenochtitlan and Tlatelolco; sometimes the meaning seems to be Tenochtitlan only, and sometimes the whole mixed Spanish-indigenous capital of New Spain. Yet since the indigenous connotation still predominates, we have not felt it appropriate to translate 'Mexico City' except in the relatively few instances where the Spanish loanword ciudad is used in addition. Let the reader understand, then, that 'Mexico' in our translation refers approximately to the area now called Mexico City. The term was not yet and long afterward would not be used for New Spain as a whole or for the country we call Mexico today."
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), 18.

ca nel mexico in ticate ca ic mani ĩ mexicayotl = For verily in Mexico were we, and thus persisted the reign of Mexico (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), 89.

ynic tiquimittazque yn ixquich yn techyahuallotoc yxquich tiquinpehuazque tiquimaçizque. yc maniz yn taltepeuh mexico. tenochtitlan. quauhtli ypipitzcayan ynetomayan. quauhtli ytlaquayan. yhuan michin ypatlanian. yhuan cohuatl yçomocayan = Thus shall we find all who lie surrounding us, all whom we shall conquer, whom we shall capture. Thus will our altepetl of Mexico Tenochtitlan be, the place where the eagle screeches and stretches itself; where the eagle eats and the fish fly and the serpent hisses.... (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. 1, 102–103.