Registrar

What Does Registrar Mean?
An institution or organization that is responsible for keeping records of bondholders and shareholders. If you are the owner of a bond or a share in a company you will be registered as a owner by one of these institutions. 

Investopedia explains Registrar
The role of the registrar is to make sure that the amount of shares outstanding in the market matches the amount of shares authorized by the company. For bonds, the registrar also makes sure that the company's obligation from a bond issue is certified as being an actual legal obligation.