The Vratya Kanda of Atharva Veda refers to the Supreme Being called Vratya, from whom Vratya Prajapati was born in the form of a golden egg. The word may be derived from vrata (vrat ‘to move’) occurring in Rig Veda (X.34.8, 12), Atharva veda II.9.1, Yajur Veda III.55, etc., having the sense of ‘multitude.’
Sayana takes the word vrata to mean ‘group’ or host (vratoh:sanghah). Mahindhara takes it to mean ‘one who conquers the groups of herotes (vrata surasamuhan sohate). In the Brahmana (XVII. 1-2) and some of Srauta Sutras refer to the vratyas as a group or class of people ousted from the Aryan society due to the breach of discipline.
In the Aryan society, education was compulsory for all dvijas (twice born); those who failed to perform the upanayana (initiation ceremony to study) were declared to be patitasavitrika and they were subjected to social boycott. Those not initiated for three generations were called vratyas. The Jain Grihyasutras call them Vrisala.
It appears that such boycotted persons formed a separate group and developed their own ways of the life. One such person realized their fault and desired to perform he upanayana, they had to perform a Vratya-Stoma rite as a prayaschitta (penitence) and could be initiated for the study of Veda, and lead a normal life.