upanayana /uːpəˈnɑːjənə/ noun1 •An initiation ceremony undergone by Hindu boys over the age of seven belonging to the highest three castes, marking the start of their formal education.An Aryan boy had to undergo the upanayana that initiated him into the study of the Veda and the sacrificial procedure, or he would never be able to build a fully realized atman. — 2006 formsupanayanas