Lexical Definition

‎ἐπόπτης‎ epóptēs (ep-op'-tace) eyewitness ^G:N-M
from ‎ἐπί‎ and a presumed derivative of ‎ὀπτάνομαι‎

eye-witness.

• a looker-on

Abbott-Smith

** ἐπόπτης, -ου, ὁ [in LXX (of God): Es 5:1, II Mac 3:39 7:35, III Mac 2:21 * ;]
1. an overseer (LXX, ll. c.).
2. a spectator: II Pe 1:16 (of ἐ. as applied to God, v. parallels in Inscr., MM, Exp., xiv; of the use of this term in the mysteries, v. Mayor on II Pe, l.c.; Thayer, s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

ἐπόπτης-ης, ου, ὁ,

(ἐπόψομαι) overseer, watcher, especially of a god, Πυθῶνος [LXX+5th c.BC+]; title of Poseidon, [Refs 2nd c.AD+]; of the Sun, [Refs 1st c.AD+]; δαίμονες ἐ. τῶν ἀνθρωπίνων [ἐπόπτηςας τῶν στρατηγουμένων 4th c.BC: Demosthenes Orator 4.25 ">Refs 5th c.BC+]; ἐ. γῆς καὶ θαλάσσης, of Pompey, [Refs]; of Augustus, [Refs]; ἐ. εἰρήνης, of a police magistrate, [Refs 4th c.AD+]

__2 simply, spectator, πόνων [Refs 4th c.BC+]
__3 inspector, [Refs 4th c.AD+]
__II one admitted to the highest grade of the mysteries, [Refs 1st c.AD+]; τινος [NT]

_{LSJ Scripture Refs: LXX.Esth.5.1 ☩ 2Pet.1.16}