Strong's G5138 — τραχύς (adjective)
trachus (trakh-oos') adj.
1. uneven, rocky (reefy)
[perhaps strengthened from the base of G4486 (as if jagged by rents)]
KJV: rock, rough 
Root(s): G4486 
Hebrew root: ῥήγνυμι
Occurrences: 2