Lexical Definition

‎ἀπόδειξις‎ apódeixis (ap-od'-ike-sis) demonstration ^G:N-F
from ‎ἀποδείκνυμι‎

demonstration.

• manifestation

Abbott-Smith

** ἀπό-δειξις, -εως, ἡ (< ἀποδείκνυμι), [in LXX: III Mac 4:20, IV Mac 3:19 13:10*;]
1. a showing off.
2. As used by Gk. philosophers, demonstration, certain proof: I Co 2:4 (v. ICC, in l.; MM, s.v.; Lft., Notes, 173).†

Abbott-Smith References

Liddell-Scott-Jones

ἀπόδειξις,

Ionic dialect -δεξις, εως, ἡ, (ἀποδείκνυμι) showing forth, making known, exhibiting, δι᾽ ἀπειροσύνην.. κοὐκ ἀπόδειξιν τῶν ὑπὸ γαίας[Refs 5th c.BC+]

__2 setting forth, publication, Ἠροδότου.. ἱστορίης ἀπόδεξις[Refs 5th c.BC+]Prooem.; ἀρχῆς ἀ. an exposition, sketch of it, [Refs 5th c.BC+]
__3 proof, βουλομένοισί σφι γένοιτ᾽ ἂν ἀ.[Refs 5th c.BC+]; χρῆσθαί τινι ἀποδείξει τινός use it as a proof of a thing, [Refs 1st c.AD+]: in plural, proofs, or arguments in proof of, τινός[Refs 5th c.BC+]; ἀ. λαμβάνειν.. τῶν μανθανόντων test them by examination, etc., [Refs 1st c.AD+]specimen, [Refs 4th c.BC+]; citation, ποιητῶν καὶ ἱστοριαγράφων ἀποδείξεις[Refs 2nd c.BC+]
__3.b in the Logic of [Refs 4th c.BC+], demonstration, i. e. deductive proof by syllogism, [Refs 4th c.BC+]; opposed to inductive proof (ἐπαγωγή), [Refs 4th c.BC+]
__4 appointment, θεωρῶν[Refs 3rd c.BC+]
__II (from middle) ἀ. ἔργων μεγάλων display, achievement of mighty works, [Refs 5th c.BC+]