Dictionary entry

ἔκδικος

G. Abbott-Smith's A Manual Greek Lexicon of the New Testament

** ἔκδικος, -ον

(< δίκη), [in LXX: Wi 12:12, Si 30:6, IV Mac 15:29 *;]

1. without law, unjust.

2. exacting penalty from; as subst., an avenger: Ro 13:4; seq. περί, I Th 4:6 (in π., a legal representative; Milligan, Th., l.c.).†