IPA: /ˈrɛdʒɪstrənt/
KK: /ˈrɛdʒɪstrənt/
A person who signs up or enrolls for something, such as an event or a service.
The registrant received a confirmation email after signing up for the conference.
Registrant → It is formed from "regist" (from Latin "registrare", meaning to record) and "-ant" (meaning one who). The word "registrant" refers to one who records or is recorded, typically in a formal context such as signing up for an event or service.
Think of someone who is 'recording' their information — 'registrant' means a person who registers or signs up.