Apparently a primary word; conquest (abstractly), i.e. (figuratively) the means of success -- victory.
Thayer's Greek Lexicon
Strong's 3529: νίκη
νίκη, νίκης, ἡ (from Homer down), victory: 1 John 5:4 (cf. νῖκος).
Englishman's Concordance (References)
Strong's Greek: 3529. νίκη (niké) — 1 Occurrence
1 John 5:4 - N-NFS GRK:ἐστὶν ἡ νίκη ἡ νικήσασα NAS: and this is the victory that has overcome KJV: is the victory that overcometh INT: is the victory having overcome
