final solution

Short definition from Wiktionary

Noun

1. 1
   The planned and attempted mass murder of the European Jews by the Nazis; the Holocaust.
2. 2
   Any similar attempted or successful genocide.
3. 3
   Used other than figuratively or idiomatically: see final, solution.

Proper noun

1. 1
   Alternative letter-case form of final solution (“attempted mass murder of the Jews by the Nazis”).