The word was coined by Horace Walpole in the 18th century, from the Persian fairy tale The Three Princes of Serendip (Serendip is an old name for the island now known as Sri Lanka)
It is used as a sociological method in Anselm L. Strauss' and Barney G. Glaserss Grounded Theory, building on ideas by sociologist Robert K. Merton, who in Social Theory and Social Structure (1949) claimed that serendipity was an Indian concept.
Serendipity is the name of a romantic movie starring Kate Beckinsale and John Cusack.