cuckoo

1. Any of various birds, of the family Cuculidae within the order Cuculiformes, famous for laying its eggs in the nests of other species; but especially a common cuckoo (Cuculus canorus), that has a characteristic two-note call. (countable, uncountable)
2. The sound of that particular bird. (countable, uncountable)
3. The bird-shaped figure found in cuckoo clocks. (countable, uncountable)
4. The cuckoo clock itself. (countable, uncountable)
5. A person who inveigles themselves into a place where they should not be (used especially in the phrase a cuckoo in the nest). (countable, uncountable)
6. Someone who is crazy. (countable, slang, uncountable)

Plural cuckoos