Mexih.

Headword: 
Mexih.
Principal English Translation: 

one of the sacred names held by the divine force also known as Huitzilopochtli, taken as an ethnic name by the migrants who were carrying him and settling Mexico-Tenochtitlan
Gran Diccionario del Náhuatl, citing A. Wimmer (2004), who quotes from Launey and other sources, https://gdn.iib.unam.mx/diccionario/mexi/54637. Translation and paraphrasing here by Stephanie Wood

Orthographic Variants: 
Mexi, Meci
Attestations from sources in Spanish: 

"... el sacerdote y señor que los guiaba, se llama Meci (Mexi), de donde toda la congregación tomó la denominación". Durán. Historia de las Indias de Nueva España (1951 I 19). Cf. Códice Ramírez. Relación del origen de los indios. 1944, 24. Cf. Cronica Mexicayotl 1949, 14-16.
Gran Diccionario del Náhuatl, citing A. Wimmer (2004), who quotes from Launey and other sources, https://gdn.iib.unam.mx/diccionario/mexi/54637