Improbability (noun)

The quality or state of being improbable; unlikeliness or improbableness.

Origin:

From late latin improbabilitās, from latin in- + probābilis ("probable"). the first recorded use of the term in english was in the early 17th century.

Examples:

1. The improbability of an event happening twice in a row is very low.
2. The improbability of a person winning the lottery twice in a row is considered high.
3. The low chance of an event happening is an example of its improbability.
4. The improbability of aliens visiting Earth is a subject of many debates.
5. The fact that he won against all odds was a testament to the improbability of his victory.