Strong's G2643 — καταλλαγή (noun)
katallage (kat-al-lag-ay') n.
1. an exchange
2. (figuratively) an adjustment, reconciliation
3. (specially) restoration to the divine favor
[from G2644]
KJV: atonement, reconciliation(-ing) 
Root(s): G2644 
Hebrew root: καταλλάσσω
Occurrences: 4