1. a legendary Spanish nobleman and philanderer who became the hero of many poems and plays and operas;
2. any successful womanizer (after the legendary profligate Spanish nobleman);
WordNet (r) 3.0 (2006):
Don Juan
n 1: a legendary Spanish nobleman and philanderer who became the
hero of many poems and plays and operas
2: any successful womanizer (after the legendary profligate
Spanish nobleman)