adj. Crazy; not sane.n. Any of various birds, of the family Cuculidae (from Latin cuculus ("cuckoo")), famous for laying its eggs in the nests of other species; but especially the common cuckoo, Cuculus canorus, that has a characteristic two-note calln. The sound of that particular bird.n. The bird shaped figure found in Swiss/German clocks (cuckoo clocks) or the clock itself.n. Someone found where they shouldn't be (used especially in the phrase 'A cuckoo in the nest'.)n. Someone who is crazy.v. To make the call of a cuckoov. To repeat something incessantly