Strong's G4243 — πρεσβεύω (verb)
presbeuo (pres-byoo'-o) v.
1. to be a senior
2. (by implication) act as a representative
3. (figuratively) preacher
[from the base of G4245]
KJV: be an ambassador 
Root(s): G4245 
Hebrew root: πρεσβύτερος
Occurrences: 2