incumbent 復習

　東京都千代田区長選で小池氏が支援する現職の区長が圧勝したことで、小池知事は都議選へ弾みをつけました。

Ward win gives Koike confidence boost for Tokyo assembly poll

An incumbent ward mayor supported by Tokyo Governor Yuriko Koike easily won re-election on Feb. 5, giving her regional party significant momentum in the battle against the dominant Liberal Democratic Party.

The election in Chiyoda Ward in downtown Tokyo was seen as a proxy war between Koike and the LDP. The results prompted her party, Tomin First no Kai (Tokyoite first group), to consider fielding more than 60 candidates in the Tokyo metropolitan assembly election scheduled for July 2.

Masami Ishikawa, 75, garnered 16,371 votes in the ward election to secure his fifth term as mayor. In a distant second place was Makoto Yosano, 41, a challenger backed by the LDP, who obtained 4,758 votes. Asao Igarashi, a 41-year-old independent, received 3,976 votes.

以下省略

http://www.asahi.com/ajw/articles/AJ201702060069.html

　今回取り上げる表現は、“incumbent”です。『ウィズダム英和辞典』(第3版、三省堂)を引いたところ、「現職の、在職[在任]中の」とありました。LDOCEでは、“the president etc at the present time”と定義されていました。
　ちなみに、「goo辞書」で語源を調べてみたところ、“cumb-(cub-)”「座る，横になる」という意味があるそうです。役職の座についている、というニュアンスから今回の“incumbent”の意味は生まれているのではないかと思います。(Blue Sky)

cf. sitting