Dictionary of Biblical Words:
We read of these 2 Cor. 3:1, and Acts 18:27. They were letters commending brethren from one assembly to another. Those generally known, such as Paul, did not of course need them. They form a valuable and scriptural guard against “false brethren creeping in unawares.”
Strong’s Dictionary of Greek Words:
Transliteration:
sustatikos
Meaning:
from a derivative of 4921; introductory, i.e. recommendatory
KJV Usage:
of commendation