official scorer
US /əˌfɪʃ.əl ˈskɔː.rər/
UK /əˌfɪʃ.əl ˈskɔː.rər/

1.
In baseball, a person appointed to record the details of a game, including hits, errors, and other statistics, and to make decisions on plays that are not clearly defined by the rules.
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The official scorer ruled the play a single, not an error.
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Fans often debate the decisions made by the official scorer.