Strong's G4889 — σύνδουλος (noun)
sundoulos (soon'-dou-los) n.
1. a co-slave, i.e. servitor or ministrant of the same master (human or divine)
[from G4862 and G1401]
KJV: fellowservant 
Root(s): G4862, G1401 
Hebrew root: δοῦλος
Occurrences: 10