The name Dionysius is a boy's name of Greek origin. Dionysius and is often added to user-created lists like Ancient Names From Antiquity and discussed in our forums with posts like "What would be the perfect twin?".
From the experts:
Dionysius was the god of wine and revelry, making the name simultaneously heavy and lightweight. One of the short forms much better. While the Romanized spelling Dionysius has been used for poets, soldiers, and saints throughout the centuries, the proper spelling of the ancient god's name is Dionysus.