understatement
//ˌʌn.dəˈsteɪt.mənt//
Noun
understatementSingular
understatementsPlural
1
A statement that represents something as smaller, less important, or less serious than it actually is.
To say the movie was 'okay' is an understatement—it was absolutely brilliant.
2
The practice or technique of deliberately minimizing the significance of something for rhetorical or ironic effect.
British humor often relies on understatement to create ironic effects.