Principal English Translation: 

literally "eagle-ruler" -- a non-dynastic, less than life-term governorship or interim ruler
James Lockhart, The Nahuas after the Conquest: A Social and Cultural History of the Indians of Central Mexico, Sixteenth through Eighteenth Centuries (Stanford: Stanford University Press, 1992), 33.

Orthographic Variants: 
quauhtlatoani, quauhtlahtoani, cuauhtlahtoani
Attestations from sources in English: 

Originally had the connotation of having achieved the position for personal merit in war, not by inheritance. Later, it simply meant one who was not laying permanent or dynastic claim to the office, although as late as the sixteenth century, the cuauhtlatoani was often a person of humble birth.

auh nimã yn cactimanca yn quauhtlahtolloc culhuacan = And then there was a vacancy; there was an interim ruler of Culhuacan
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, 66–67.