Serendipitously is a word that refers to an unexpected, fortunate occurrence. Some synonyms for serendipitously include coincidentally, fortuitously, unexpectedly, and happenstantially. A serendipitous moment can occasionally be described as a lucky coincidence, an unexpected break, or a happy accident. Other words that might be used to describe this kind of serendipitous moment could be propitious, auspicious, or fateful. Serendipitous moments are often considered as moments of good luck or providence, and when something happens serendipitously, it can often lead to a positive outcome or result. Whatever words one decides to use, a serendipitous moment is always a welcome surprise.