dvija

Hence, in the later classical Sanskrit literature, the term dvija, or twice-born, is used simply as a synonym for a Brahman.

Other titles of Brāhmans are Dvija, or twice-born, that is, one who has had the thread ceremony performed; Bipra, applied to a Brāhman learned in the Shāstras or scriptures; and Srotriya, a learned Brāhman who is engaged in the performance of Vedic rites.

By its performance he becomes Dvija or twice-born, and the highest importance is attached to the change or initiation.