The Spanish word "sierra" is usually applied to mountain ranges or ridges. However, a few mountains were given the name "sierra" after the Conquest, like "Sierra de Tlaxcala" or "Sierra de Tolocan" (now outdated names for Malinche and Nevado de Toluca, respectively). As listed by the Mexican geographical institute INEGI, the official name for the Sierra Negra ("Black Mountains") is Cerro La Negra ("Black Lady Hill"), although the latter is largely unused in common speech. The Nahuatl names Tliltépetl ("Black Mountain") or Atlitzin ("Our Lord (or Lady) of the Waters") are sometimes attached. Speakers of Orizaba Nahuatl called the mountain "Iztactepetl Icni" ("Sibling of the White Mountain"; the "White Mountain" being the Pico de Orizaba).