1. a bird known for laying its eggs in other birds’ nests and for its distinctive two-note call
2. the sound made by a cuckoo bird or a cuckoo clock

1. crazy or silly
Usage: informal

Examples

• The cuckoo laid its egg in the robin’s nest.
• We heard the cuckoo calling from the forest.
• The cuckoo clock chimed twelve times at noon.
• The wooden bird popped out with a cheerful cuckoo sound.
• My grandmother’s cuckoo clock was her prized possession.
• He went completely cuckoo after staying up all night.
• That’s a cuckoo idea if I ever heard one.