“Vrisham” means dharma.
Once upon a time, it is said the goddess of dharma did penance for the same of the lord of Tirumala.
She wanted god to empower her to dispense dharma dispassionately and flourish. Srinivasa conceded her desire.
From then on, it came to be known as Vrishachalam or Vrishadri.
A great devotee of Lord shiva named Vrishabhasura is a demon who is cruel and wicked.
There was a fierce fight between demon and Sri Hari (in form of hunter), at last srinivas released his sudharshana disc.
Realizing the inevitability of his death, Vrishabha prostrated before the lotus feet of Lord and sought his refuge. “Oh, Lord srinivasa! Please forgive me. I feel it my past fortune to be killed by your great disc. I seek a favour from you and I am sure you are kind enough to concede the same. That is, this hilly area of mine should assume my name and be known as Vrishabhachala.
I also implore upon you to stay here as Vrishabhadripathi, the lord of Vrishabhadri.”
Granting his prayers, Srinivasa ended up the demon. Thus, the hill came to be known as Vrishabhachala.