Understatement

/ˌʌndərˈsteɪtmənt/

Synonyms

  • reduction
  • downplaying
  • minimization
  • trivialization

Slang Meanings

It's an understatement.
When she said the movie was 'not great,' it was an understatement considering how bad it was.
Underplaying it.
He was really underplaying it when he called the storm 'a bit windy.'