From the combination of the words, eternal happiness (hrishika) and the attributes of divinity (isha) is he called Hrishikesha. He is known as Mahabahu in the Smritis, as by his two arms he supports the earth and the sky.
हर्षात् सुखात् सुखैश्वर्याधृषीकेशत्वमश्नुते। बाहुभ्यां रोदसी बिभ्रन्महाबाहुरिति स्मृतः॥