- petrous (adj.)
- 1540s, from Middle French petreux, from Latin petrosus "stony," from petra "rock," from Greek petra "rock, cliff, ledge, shelf of rock, rocky ridge," of uncertain origin. Possibly from PIE root *per- (2) "to lead, pass over," if the original meaning is "bedrock" and the notion is "what one comes through to" [Watkins].
