1. a bird with a distinctive two-note call, known for laying its eggs in other birds' nests

1. crazy or silly; not sensible
Usage: informal

1. to make the call of a cuckoo bird

Examples

• We heard a cuckoo calling in the forest early in the morning.
• The cuckoo bird is famous for tricking other birds into raising its chicks.
• He's a bit cuckoo if you ask me—he talks to himself all day.
• The old clock cuckoos on the hour.
• That idea is completely cuckoo; it will never work.
• The cuckoo's distinctive call echoed through the woods.