Petra is the feminine of Peter — from the Greek petros (πέτρος), meaning "rock" or "stone." Jesus called Simon "Cephas" (Aramaic for rock), which was translated into Greek as Petros (Peter). Petra is also the name of the ancient rose-red city carved into rock cliffs in southern Jordan, now a UNESCO World Heritage Site.
Petra is widely used across Eastern Europe (especially Czech Republic, Slovakia), Germany, Scandinavia, and parts of South America. In the U.S. it sits in the top 800 and is rising. The Czech tennis player Petra Kvitová is a famous bearer.
Petra reduces to nine — the number of bedrock strength.