By-election
Election to fill a vacant political office
A by-election (also spelled bye-election in Ireland), known as a special election in the United States and the Philippines, or a bypoll in India, is an election used to fill an office that has become vacant between general elections. A vacancy may arise as a result of an incumbent's death or resignation, when the incumbent becomes ineligible to continue in office (because of a recall, a prohibited dual mandate, criminal conviction, or failure to maintain a minimum attendance), or when an election is invalidated by voting irregularities. In some cases, a vacancy may be filled by a method other than a by-election (such as the outgoing member's party nominating a replacement), or the office may be left vacant.
From Wikipedia, under CC BY-SA. More on occurri.