Русско-англо-русский юридический словарь

Generally, a snap election in a parliamentary system (the dissolution of parliament) is called to capitalize on an unusual electoral opportunity or to decide a pressing issue, under circumstances when an election is not required by law or convention. (Wikipedia)

Spanish Prime Minister Pedro Sánchez on Monday said he would dissolve parliament and call for a snap election for July 23, a day after conservatives and the far right posted strong gains in regional and municipal polls. (Politico)

In Russia, under the 1993 constitution, according the article 109, while the State Duma (lower house of the Federal Assembly) is elected for a five-year term, but the president has the authority to dissolve the State Duma and call a snap election. (Wikipedia)