To win a victory, defeat an opponent, or prevail in a contest. The noun nike (G3529, victory) is the related term. In Revelation nikao appears repeatedly as a present-tense call to perseverance: 'to the one who overcomes...' — framing the Christian life as a sustained struggle that ends in victory.
Revelation's seven letters each promise a reward 'to the one who overcomes (nikao).' The implied model is Christ himself: John 16:33 declares 'I have overcome (nenikeka) the world' — a perfect tense indicating ongoing victory from a completed act. The Christian participates in this victory not by personal strength but by 'the blood of the Lamb and the word of their testimony' (Rev 12:11). 1 John 5:4 grounds the victory in faith: 'this is the victory (nike) that has overcome the world — our faith.'