A snap election is an election called earlier than expected.

Snap election
Snap Election
Snap Election
The snap election in Austria, September 2008
The 2017 Austrian snap election: a shift rightward
Nationalism and the 2014 Snap Election: The Abe Conundrum
Reading PIBOR futures options smiles: The 1997 snap election
Back to a Predominant Party System: The November 2015 Snap Election in Turkey
Morgan Stanley: Theresa May's final Brexit deal could trigger a snap election
Do (Some) Canadian Voters Punish a Prime Minister for Calling a Snap Election?
Reading Interest Rate and Bond Futures Options' Smiles Around the 1997 French Snap Election
Reading Interest Rate and Bond Futures Options' Smiles Around the 1997 French Snap Election
The Electoral Consequences of Election Timing: Estimating the Popularity Cost of Calling a Snap Election