Lexical Definition

‎ἀποδείκνυμι‎ apodeíknymi (ap-od-ike'-noo-mee) to display ^G:V
from ‎ἀπό‎ and ‎δεικνύω‎

(ap-)prove, set forth, shew.

• to show off, i.e. exhibit
• figuratively, to demonstrate, i.e. accredit

Abbott-Smith

ἀπο-δείκνυμι, [in LXX: Es 2:9 (ראה), al.;]
1. to bring out, show forth, exhibit (Lft., Notes, 200; ICC, in l.): I Co 4:9.
2. to declare, show: Ac 2:22.
3. to prove: Ac 25:7.
4. As freq. in late Gk., to proclaim to an office: seq. ὅτι, II Th 2:4 (Milligan, in l.; MM, s.v.; Lft., Notes. 113.)†

Abbott-Smith References

Liddell-Scott-Jones

ἀποδείκνυμι-νῡμι

(and ἀποδεικνύω [Refs 5th c.BC+], Ionic dialect ἀποδέκνῦμι [Refs 5th c.BC+]future -δείξω, Ionic dialect -δέξω:—

__A point away from other objects at one, and so:
__A.I point out, display, make known, whether by deed or word, σφι γνώμας[Refs 5th c.BC+]; proclaim, τὴν ἡμέρην “GDI” [same place];—passive, τῶν οῠρων ἀποδεχθέντων[Refs 4th c.BC+]
__A.I.2 bring forward, produce, μαρτύρια τούτων[Refs 5th c.BC+]participle, ὑγιέα τινὰ ἐόντα ἀ. produce him safe and sound, [Refs 5th c.BC+]
__A.I.3 produce, deliver accounts, τὸν λόγον[Refs]
__A.I.4 publish a law, [Refs 5th c.BC+]
__A.I.5 appoint, assign, τέμενος ἀ. τινί[Refs 5th c.BC+]; τὴν τρίτην ἀ. ἐκκλησίαν to fix, prescribe it, [Refs 4th c.BC+]:—passive, τοῖσί ἐστι χῶρος ἀποδεδεγμένος[Refs 5th c.BC+]
__A.I.5.b with infinitive, κώμας ὅθεν ἀπέδειξαν οἱ ἡγεμόνες λαμβάνειν τὰ ἐπιτήδεια whence they appointed that they should receive.., [Refs 5th c.BC+] —passive, τοῖσι ἀποδεδέχθαι.. ἕλκειν (impersonal) it had been appointed them to draw, [Refs 5th c.BC+]
__A.I.6 show by argument, prove, demonstrate, [Refs 5th c.BC+]; ὅτι.. [Refs]; πότερον.. ἢ.. [Refs]: with double accusative, prove one so and so, οὓς ἀποδείξω λέκτρων προδότας[Refs 5th c.BC+]: followed by participle, ἀ. λόγῳ.. οὐδὲν μετεόν[Refs 5th c.BC+]; ἀ. τινὰ λέγοντα οὐδέν make it evident that.., [Refs]
__A.II show forth a person or thing as so and so, hence:
__A.II.1 appoint, proclaim, create, ἀ. τινὰ στρατηγόν[Refs 5th c.BC+]: with infinitive, στρατηγὸν εῖναι[Refs 5th c.BC+]; ἀ. τούτους τὴν πόλιν νέμειν[NT]:—passive, to be so created, [Refs 5th c.BC+]; ὕπατος ἀποδεδειγμένος, = Latin consul designatus, [Refs]
__A.II.2 make, render, mostly with an adjective, ἀ. τινὰς μοχθηροτάτους make them finished rascals, [Refs 5th c.BC+]: with a substantive, γέλωτα ἀ. τινά[Refs]: with participle, βλέποντ᾽ ἀποδείξω σ᾽ ὀξύτερον τοῦ Λυγκέως[Refs 5th c.BC+] —passive, πολέμιοι ἀποδεδειγμένοι declared enemies, [Refs 5th c.BC+]
__A.II.3 represent as, ἀ. παῖδα πατρὸς ἑωυτῶν ἕκαστον ἐόντα[Refs 5th c.BC+]:— passive, ἀνδραγαθίη δ᾽ αὕτη ἀποδέδεκται is represented, considered as.., [Refs 5th c.BC+]; οὐδὲ.. οὗτοι ἐν τοῖσι ἄλλοισι θεοῖσι ἀποδεδέχαται have not been considered, admitted among.., [Refs]:—these two last examples may be passive usages of ἀποδέχομαι.
__A.II.4 with infinitive, ordain a thing or person to be, [Refs 5th c.BC+]
__A.II.5 dedicate, consecrate, θέατρον[Refs 1st c.AD+]:—passive, νεὼς ἀποδέδεικται[Refs 2nd c.AD+]
__B middle, show forth, exhibit something of one's own, ἀποδέξασθαι τὴν γνώμην deliver one's opinion, [Refs 5th c.BC+]; ἀ. ἀρετάς display high qualities, [Refs 5th c.BC+]; of buildings and the like, μνημόσυνα ἀ.[Refs 5th c.BC+]; οὐδεμίαν στρατηΐην ἀ. not to have any military service to show, [Refs]:—passive, ἔργα μεγάλα καὶ θαυμαστὰ.. ἀποδεχθέντα [Refs]
__B.2 middle in active sense, ἀποδεδειγμένοι ἦσαν ὅτι had declared that.., [Refs 5th c.BC+]
__C passive, see above [Refs]aorist ἀπεδείχθην is always passive, as [Refs 5th c.BC+]; and so mostly perfect ἀποδέδειγμαι,[Refs 5th c.BC+]; but the participle of the latter is sometimes active, see above [Refs 5th c.BC+]

_{LSJ Scripture Refs: 2Thess.2.4}