1 an occasion when something that was joined together or united breaks into separate parts: --
He had what he calls a "crack-up" when he was a young journalist.
The empire became ungovernable, resulting in a total crack-up.
The story depicts the crack-up of the writers' own partnership.
2 someone or something that is very funny: --
I wonder if they'll still find me a crack-up when they get to know me.
He was a victim of the too-much-too-soon celebrity crack-up syndrome.
He is unsparing in his description of the crack-ups, shell-shock and drunkenness that affected the troops.
Agatha Christie's marriage to her first husband Archie was followed by her famous crack-up and disappearance.
What she conveys excellently is the way families observe social rituals while ignoring psychological crack-ups.
They argue that the period is best characterised as one involving policy change and instability, since the crack-up of the consensus in the 1960s.
Following the great Democratic crack-up, she may be the best person to put her party together again.