Last week, we saw that Kunti’s baby was found by the Anga Pradesh younger prince Adiratha and because he had golden earrings and armour, he was named Vasusena. He was also called Vrisha. But then, when did he come to be called Karna?

 
This happened much later. Just before the Pandava's agyaatvaas, Suryadev came to Karna in a dream and told him that Indra  was going to visit him soon to take the divine Kavach kundal away. He advised his son Vasusena not to give the two away as they kept him alive. But Karna did not want to do that.

So Suryadev told him to ask for something in exchange that would help him achieve his fondest goal- killing Arjuna. He suggested asking for a powerful weapon that could kill Arjuna. Karna found this to be a good suggestion and he awaited Indradev’s arrival.

As Suryadev had warned him, Indra appeared in the garb of  Brahman and asked for the Kavach kundal. Karna repeatedly refused to part with them, offering riches, cows and more to the Brahmana. Finally, Karna revealed that he knew that this was Indra before him.

Indra came into his own form now. Karna said that he would not give the kavach kundal to the King of Gods without getting something in return. Indra asked him what he wished to have and Karna got his chance to ask for a powerful weapon that would kill his enemy.

Indra agreed to give him the Vasavi Shakti- a weapon that would not miss the enemy and would kill anyone it was aimed at. The King of gods thought of the Vasavi Shakti and it came to him at once. He gave it to Karna, who happily accepted it.

 
With the Vasavi shakti in his arsenal, Karna was now willing to give the kavach kundal. He cut them both away from his body and gave them to Indra. This is how his name came to be Karna- for cutting away the divine protection from his body.

So, the name Karna came to him just more than a year before the Kurukshetra war. For the major portion of his life, Karna was known as Vasusena/ Vrisha.
Since the Mahabharata was told to Janamejaya years after the war, Sage Vaishampayana uses the name Karna to refer to Kunti and Surya’s son, who was adopted by Adiratha.

Interestingly, Yuyutsu, the son of Dhritarasthra and Gandhari’s maid, was also known as Karna.