Quick Definition
ἔνδειξις, εως, ἡ n.f. a showing, proof, demonstration, sign
Strong's Definition
from 1731; indication (abstractly)
KJV Usage: declare, evident token, proof
UBS Dictionary of the Greek New Testament
noun, f. | -εως | δείκνυμι
1 As in the case of βέβαιος[c] (28.43), βέβαιοω[b] (28.43), and βεβαίωσις (28.44), there are two distinct sets of semantic features in the series ἔνδειξις, ἔνδειγμα, and ἀπόδειξις. The element of showing or demonstrating implies clearly making something known, but that which is made known is done in a clear, convincing, and confirming manner and therefore shown to be certain or true. This double set of semantic features is contained in such terms as proof, evidence and confirmation.
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
ἔν-δειξις, -ews, ἡ, (ἐνδείκνυμι), demonstration, proof: i.e. manifestation, made in act, τῆς δικαιοσύνης, Ro. iii. 25 sq. ; τῆς ἀγάπης, 2 Co. viii. 24; i. q. sign, evidence, ΓΑ. V. evident token], ἀπωλείας, Phil. i. 28. [Plat., al.]
Mounce Concise Greek Dictionary
ἔνδειξις endeixis 4x
a pointing out; met. manifestation, public declaration, Rom. 3:25, 26; a token, sign, proof, i.q. ἔνδειγμα, 2 Cor. 8:24; Phil. 1:28*
Abbott-Smith Greek Lexicon
* ἔν-δειξις, -εως, ἡ
(< ἐνδείκνυμι),
a pointing out, showing forth, proof (v.s. ἔνδειγμα): Ro 3:25, 26, II Co 8:24, Phl 1:28.†
Liddell-Scott-Jones — Greek-English Lexicon
ἔνδειξις (endeixis) — demonstration. ἔνδειξις, εως, ἡ, indication, ἔνδειξιν τῷ λόγῳ ἐνδείκνυσθαι, opposed to ἐννοεῖν, [NT+5th c.BC+]
2. as law-term, laying of information against one who discharged public functions for which he was legally disqualified, writ of indictment in such a case, [Refs 5th c.BC+]
II. demonstration, display of one's good will [Refs 4th c.BC+]
III. proof, demonstration, [Refs 6th c.AD+]