Petrus is a Latin name derived from the Greek meaning "rock", and is the common English prefix "" used to describe rock-based substances, like petros-oleum or "rock oil." As the source of Peter, it is a common name for people from antiquity through the medieval era. In the Netherlands and South Africa it remained a a very common given name, though in daily life, many use less formal forms like Peter, Pierre, Piet and Pieter.