A judge — a person who scores or officiates in sports or competitions, especially in judged events.
体操大会のジャッジは非常に厳しかった。
The judges at the gymnastics competition were very strict.
ボクシングのジャッジが判定を下した。
The boxing judge gave the decision.
ジャッジ席から選手の演技をチェックしていた。
They were checking the athletes' performances from the judges' seats.
A judgement or decision — the result of an evaluation or call, often used in sports or contests (can be used as a noun or with suru).
最終的なジャッジは大会本部が下すことになっている。
The final judgment is to be made by the tournament headquarters.
審査員のジャッジが結果を左右した。
The judges' decisions affected the outcome.
その問題はジャッジが分かれるだろう。
That issue will probably split the judges' decisions.
The act of judging or evaluating — often used as 'ジャッジする' to mean to judge or make a decision about someone or something.
審査員は参加者の演技を公正にジャッジした。
The judges fairly evaluated the participants' performances.
他人をすぐにジャッジするのはよくない。
It's not good to judge others quickly.
彼の能力をジャッジするのは難しい。
It's difficult to judge his ability.