combining form
or petri- or petro-
Etymology: Middle French petr-, petri- & Latin petr- & New Latin petro-, from Greek petr-, petro-, from petros stone & petra rock
1.
a. : stone : rock
petr escent
Petri cola
petro genesis
b. : petroleum
petro porphyrins
2. : of or relating to the petrous portion of the temporal bone and
petro hyoid