1The happenstance discovery of penicillin revolutionized the treatment of bacterial infections.
2Was it mere happenstance that the two old friends ran into each other at the airport?
3The company's success was not solely due to strategic planning, but also to a degree of happenstance.
4Try to capitalize on the happenstance opportunities that arise in your daily life.
5Some scientists argue that the emergence of life on Earth was the result of happenstance rather than a predetermined process.