Generally people say, "God is great." But they do not know how great He is. God's greatness is indicated perfectly by the name "Krishna." If you want a perfect definition of the word "God," then it is Krishna, because the word Krishna means "all-attractive." Unless one is all-attractive, how can He be God, the greatest? If one is great, he must be attractive. For example, John D. Rockefeller and Henry Ford were considered great men because they were very rich, and their great wealth made them attractive. So wealth is one feature of attraction. Therefore God must be the most wealthy person. Beauty is another attractive feature—so God must be the most beautiful person. Many people, when they see a picture of Krishna, are convinced they have never seen such a beautiful person, although He's a little blackish. Similarly, Krishna fully possesses the attractive opulences of strength, wisdom, fame, and renunciation. And because these six opulences of infinite wealth, beauty, strength, wisdom, fame, and renunciation make Him all-attractive, God is known by the name "Krishna." With these transcendental opulences He can attract the richest person, the most beautiful person, the strongest person, the wisest person, the most famous person, and the most renounced person. Such infinite attractive features are impossible for us to understand through mental speculation based on sense perception, and so Krishna is also known as Adhoksaja.
Srila Prabhupada's book: Dharma: The way of Transcendence