#1558 ἔκδικος ekdikos {ek'-dik-os}

 from G1537 and G1349; TDNT - 2:444,215; adj

—Greek Word Study (Transliteration-Pronunciation Etymology & Grammar)

 1) without law and justice
 2) exacting penalty from one
    2a) an avenger, punisher

—Thayer's (New Testament Greek-English Lexicon)

—Strong's (Greek Dictionary of the New Testament)

—NAS Exhaustive Concordance of the Bible with Hebrew-Aramaic and Greek Dictionaries

 AV - avenger 1, revenger 1; 2

—Exhaustive Concordance (KJV Translation Frequency & Location)