Definition of petrus:
(N) :
the third archbishop of Uppsala, Sweden, between 1187 and 1197.
(N) :
the Latin form of the Greek name Πέτρος (pétros) meaning "rock", and is the common English prefix "petro-" used to describe rock-based substances, like petros-oleum or "rock oil."
(N) :
Flavius Petrus was a Roman politician during the reign of Theodoric the Great.