Strong's G2872 — κοπιάω (verb)
kopiao (kop-ee-ah'-o) v.
1. to feel fatigue
2. (by implication) to work hard
[from a derivative of G2873]
KJV: (bestow) labour, toil, be wearied 
Root(s): G2873 
Hebrew root: κόπος
Occurrences: 23