Strong's G4526 — σάκκος (noun)
sakkos (sak'-kos) n.
1. "sack"-cloth, i.e. mohair (the material or garments made of it, worn as a sign of grief)
[of Hebrew origin (H8242)]
KJV: sackcloth 
Root(s): H8242 
Hebrew root: שַׂק
Occurrences: 4