What is the meaning of Krishna ?
कृष्णवर्णात्मकत्वाद्वा कृष्ण: – Due to his black color (कृष्ण वर्ण) , He is called as Krishna
कृषिर्भूवाचक: शब्दो णश्च निवृत्तवाचकः।
विष्णुस्तद्भावयोगाच्च कृष्णो भवति शाश्वत: – Mahabharata Udyogparva 70.5
This word ‘कृष्’ represent existence and ‘ण’ represents bliss , because Lord Vishnu has these two qualities therefore he is called Krishna कृष्ण
कृषामि मेदिनीं पार्थ भूत्वा कार्ष्णायसो हल:
कृष्णो वर्णश्च मे यस्मात्तस्मात्कृष्णोऽहमर्जुन – Mahabharata Shantiparva 342.79
O Partha! I cultivate this earth by using black iron plough and my color is black, therfore O Arjuna ! I am Krishna.