Caprice (noun)

1. A sudden, unpredictable change of mood or behavior.
2. A sudden desire or change of mind, especially if it is unlikely or inconvenient.

Origin:

From the french word "caprice" meaning "whim".

Examples:

1. He decided to leave on a trip on a caprice.
2. She changed her mind at the last minute, due to a caprice.
3. He was known for his caprices and sudden changes of plans.
4. The concert was cancelled due to the caprice of the weather.
5. It was a caprice of fate that they met again.