Persistence (noun)

1. The quality of continuing to exist or occur despite difficulties.
2. The quality of continuing to do something despite difficulties or opposition.

Origin:

Middle english, from latin persistentia, from persistere.

Examples:

1. Her persistence paid off and she finally landed the job.
2. His persistence in the face of adversity is admirable.
3. The persistence of the virus is a concern for public health.
4. The persistence of the species is a marvel of nature.
5. The persistence of the problem is frustrating.