election day; polling day
Refers to the specific day on which voting takes place in an election.
投票日は日曜日になることが多い。
Election day often falls on a Sunday.
投票日には必ず投票に行きます。
I always go to vote on election day.
Compound of 投票 (とうひょう, 'voting') and 日 (び, 'day').