Initiation is a rite of passage marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components. In an extended sense, it can also signify a transformation in which the initiate is 'reborn' into a new role.
initiation (ɪˌnɪʃɪˈeɪʃən) n 1. the act of initiating or the condition of being initiated 2. the often secret ceremony initiating new members into an organization