olemus
Wiktionary:
1. an official keeper or recorder of records
4. (Internet) a service that manages domain names

näiteid
domain name registrar -- domeeninimede registraator
registrar of a cadastre -- maakadastri pidaja
registrar of companies -- äriregistri pidaja
registrar of deeds -- kinnistusametnik

https://en.wikipedia.org/wiki/Domain_name_registrar