initiate /ɪˈnɪʃiˌeɪt/ verb
[+ object]
1 formal : to cause the beginning of (something) : to start or begin (something)
2 to formally accept (someone) as a member of a group or organization usually in a special ceremony
3 to teach (someone) the basic facts or ideas about something — usually + into
— initiator /ɪˈnɪʃiˌeɪt̬ɚ/ noun