yayactzintli.

Headword: 
yayactzintli.
Principal English Translation: 

a weakling (see Chimalpahin); could also share the definition for yayactzin, "animal o cosa de color muy oscuro, que se acerca a negro; animal or object with a very dark color, almost black" or yayactontli, "blackish, dark"
See, for example, https://quizlet.com/190147199/22-other-level-2-flash-cards/ and https://www.scribd.com/document/138177186/Nauatl-vocabulary-docx

Attestations from sources in English: 

çan yayactzintli catca amo qualxayaque yhuan çan pitzahuactzintli catca amo nacayo = she was quite weak, had not a pretty face, was quite thin, was not fleshy. (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, 136–137.