1580s, from Middle French initiation or directly from Latin initiationem (nominative initiatio) "participation in secret rites," noun of action from past participle stem of initiare "originate, initiate," from initium "a beginning" (see initial (adj.)).
his initiation into the club
she looked forward to her initiation as an adult
his dullness was due to lack of initiation
initialese
initialism
initialize
initiand
initiate
initiation
initiative
initiatory
in-itselfness
inject
injection