The name Krishna means...
A few references discussing why Krishna is called "Krishna."
A selection of Srila Prabhupada's commentaries and conversations about the name "Krishna," including its Sanskrit etymology (word origin). Where possible, we've provided links for further exploring the topic or obtaining your own copy of the book quoted.
The meaning of the name "Krishna":
"The name Krishna means 'all-attractive.' God attracts everyone; that is the definition of 'God.' We have seen many pictures of Krishna, and we see that He attracts the cows, calves, birds, beasts, trees, plants, and even the water in Vrindavana. He is attractive to the cowherd boys, to the gopis, to Nanda Maharaja, to the Pandavas, and to all human society. Therefore if any particular name can be given to God, that name is 'Krishna.'"
Etymology of the word 'Krishna':
''The word 'krish' is the attractive feature of the Lord's existence, and 'na' means spiritual pleasure. When the verb 'krish' is added to the affix 'na' it becomes Krishna, which indicates the Absolute Truth.''
—Mahabharata (Udyoga-parva, 71.4)
The etymology of the name 'Krishna':
If we analyze the nirukti, or semantic derivation, of the word 'Krishna,' we find that na signifies that He stops the repetition of birth and death, and krish means sattartha, or 'existence.' (Krishna is the whole of existence.) Also, krish means 'attraction,' and na means ananda, or 'bliss.'
The name 'Krishna,' meaning 'all-attractive,' can be applied only to God:
Srila Prabhupada: ... Krishna means 'all-attractive.'
Bob: Oh, I see.
Srila Prabhupada: Yes. God has no name, but by His qualities we give Him names. If a man is very beautiful, we call him 'beautiful.' If a man is very intelligent, we call him 'wise.' So the name is given according to the quality. Because God is all-attractive, the name Krishna can be applied only to Him. Krishna means 'all-attractive.' It includes everything.