Meiosis:
The ironic minimizing of fact, understatement presents something as less significant than it is. The effect frequently can be humorous and emphatic.

Example:
Fire and Ice
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great and would suffice.
-Robert Frost

Explanation:

Frost uses meiosis in this poem, which is evident in the last line. He says "and would suffice". He is saying death by ice would be adequate, which is an understatement. It death is horrific and more than just satisfying. The purpose of Frost doing this shows he does not fear death, and even though it is an understatement it heightens the dramatic tension. It also helps set the detached yet depressing tone and mood.