IPA: /əˈfɪʃənt/
KK: /əˈfɪʃənt/
A person who leads or conducts a religious ceremony or service, such as a wedding or baptism.
The officiant guided the couple through their wedding vows.
Officiant is derived from "officium" (meaning duty or service) and the suffix "-ant" (indicating a person who performs an action). The word refers to a person who performs a duty or service, particularly in a ceremonial context.
Think of someone performing a 'duty' ('officium') — that's what an officiant does, they are the person who carries out a specific service.