1. Comical, outlandishly extravagant: Many people prefer zany comedy to sophisticated humor.
2. Nonsensical, hairbrained, or bizarre: Come on, Ralph, don't be such a zany person. Be serious for a change.
3. Etymology: Giovanni (John) was for a long time a common name in Italy, and in Venice a pet name for Giovanni is Zanni.

Venetians must have had a lot of servants called Zanni because the name became associated with a type of clown or buffoon who played humorous servants in early Italian comedies or a commedia dell'arte.

From this clownish character, the zanni, we get the English word zany.