1. crazy or silly
Usage: informal

1. a crazy or silly person
Usage: informal

Examples

• That’s a completely loony idea!
• He went loony after working too many hours.
• Don’t listen to that loony – he doesn’t know what he’s talking about.
• The whole plan sounds loony to me.
• She acted loony at the party last night.
• Everyone thought he was a loony until his invention made millions.