Serendipity (noun)

1. The occurrence and development of events by chance in a happy or beneficial way.
2. The faculty of making fortunate and unexpected discoveries by accident.

Origin:

From the persian word "serendip" which is the old name of sri lanka, it was first used in english by horace walpole in 1754 to describe the unexpected discovery of something desirable.

Examples:

1. The discovery of penicillin was a serendipitous accident.
2. Her promotion was a result of serendipity.
3. It was serendipity that brought them together.
4. The invention of the telephone was a serendipitous outcome of Alexander Graham Bell's experiment.
5. He attributed his success to a combination of hard work and serendipity.