IPA: //əˈdʒuːdɪkeɪtə//
KK: /ədˈʒudɪˌkeɪtər/
A person who makes a decision or judgment in a dispute or competition, often in a legal or formal context.
The adjudicator made a fair decision in the dispute between the two parties.
Adjudicator is formed from "ad-" (meaning to) and "judicare" (meaning to judge). The word refers to a person who judges or makes decisions, particularly in a legal context, thus someone who adjudicates.
Think of someone who 'judges' ('judicare') something 'to' a conclusion ('ad-') — that's why an adjudicator is a person who makes judgments.