Cierra /cier-ra/ [2 sylls.] as a name for girls. Cierra's roots are Irish, Gaelic and Spanish, and the name Cierra means black; saw. Cierra is an alternate form of Ciara (Irish, Gaelic).Cierra is also a derivative of Sierra (Spanish): place name for the western mountains.Kreatif forms: Cierla, Cierma, Cierri.ierra is a very prominent first name for females (#1751 out of 4276, Top 41%) and a slightly less prominent last name for both adults and children (#80216 out of 150436, Top 53%). (2000 U.S. Census). Displayed below is the birth name popularity of Cierra for girls.