initiation
US /ɪˌnɪʃ.iˈeɪ.ʃən/
UK /ɪˌnɪʃ.iˈeɪ.ʃən/

1.
the action of beginning something
:
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The initiation of the new project will take place next month.
•
Her initiation into the company was smooth.
2.
the process of being formally accepted into a group or organization, typically with a ritual
:
•
The secret society held a complex initiation ceremony.
•
He underwent a rigorous initiation to join the fraternity.