Quick Definition
ἐξισχύω v. I have strength for, am perfectly able
Strong's Definition
from 1537 and 2480; to have full strength, i.e. be entirely competent
KJV Usage: be able
UBS Dictionary of the Greek New Testament
verb | ἰσχύω
74.10 · Able, Capable
to be completely able, to be fully able to be completely capable of doing or experiencing something
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
ἐξ-ισχύω : 1 aor. subjune. 2 pers. plur. ἐξισχύσητε, to be eminently able, to have full strength, [cf. ἐκ, VI. 6]: foll. by an inf. Eph. iii. 18. (Sir. vii. 6; rare in Grk. writ., as Dioscor., Strab., Plut.)
Mounce Concise Greek Dictionary
ἐξισχύω exischuō 1x
to be fully able, be strong, Eph. 3:18*
Abbott-Smith Greek Lexicon
**† ἐξ-ισχύω
[in LXX: Si 7:6 * ;]
to have strength enough, to be quite able: c. inf., Eph 3:18.†
Moulton & Milligan — Vocabulary of the Greek NT
ἐξισχύω. BGU LI. 275" (A.D. 215) καὶ ἐπείρασαν αὐτὴν (sc. μηχανὴν) ἐπανοῖξαι Kal οὐκ ἐξείσχυσαν, P Oxy VIII. 11207 (early ᾿Εξέστην occurs in BGU | 24 ἐξομολογέω iii/A.D.) ἀλλὰ οὗτος ἐξείσχυσεν τὰ βιβλείδια ἀθετηθῆναι, *‘but his influence procured the failure of the petition” (Ed.). See also Vett. Val. p. 288!% πολλάκις yap ὑπ᾽ ὄψιν προδείξαντες τὸ ἀποτέλεσμα ἠτόνησαν διὰ τὸ ἐπὶ δυναστικοῦ τόπου ἕτερον τετευχότα ἐξισχῦσαι. These examples make it at least doubtful whether it is possible to give the verb the intensive meaning ‘‘ be fully able,”’ ‘‘ be strong ’’ (RV), often assigned to it in Eph 38.
Liddell-Scott-Jones — Greek-English Lexicon
ἐξισχύω (exischuō) — to have power. ἐξισχύω [ῡ], have strength enough, be able, ὥστε ποιεῖν [Refs 1st c.BC+]: with infinitive only, [LXX+NT+1st c.AD+]; ἐξίσχυσεν τὰ βιβλείδια ἀθετηθῆναι procured the rejection of the petition, [Refs 3rd c.AD+]: absolutely, prevail, [Refs 1st c.BC+]
II. with genitive, τὸ δαιμόνιον παίδων ἐξισχῦον fate prevailing over the children, [Refs 2nd c.AD+]
III. middle, of flames, gather force, [Refs 4th c.BC+]