This is the 380th most frequent Russian word.
чемпионата
"Чемпионата" translates to "of the championship" in English.
In this sentence, "чемпионата" is used in the genitive singular case, indicating the association of the championship with its subject: chess.
Он был победителем чемпионата по шахматам.
He was the champion of the chess championship.
In this context, "чемпионата" denotes possession or affiliation, describing participants that are taking part in the championship.
Участники чемпионата по бегу были очень подготовлены.
The participants of the running championship were very prepared.
Here, "чемпионата" is in the genitive singular case, detailing the occurrence (time) of an event during the championship.