Look up unseat in Wiktionary, the free dictionary.
Political term about incumbents losing elections
Unseating is a political term which refers to a legislator who loses their seat in an election. A legislator who is unseated loses the right to sit in a legislative chamber. A landslide victory results in many legislators being unseated.
When an incumbent Member of Congress runs for re-election they may be unseated in the general election. This is more likely if the politician represents a swing state or swing district.