adjudicator

Concise Oxford English Dictionary © 2008 Oxford University Press:
adjudicate /əˈdʒuːdɪkeɪt/

▶verb make a formal judgement on a disputed matter.

■ act as a judge in a competition.

– derivatives
adjudication noun,
adjudicative adjective,
adjudicator noun.

– origin C18 (earlier (C17) as adjudication): from L. adjudicat-, adjudicare (see adjudge).