Synonyms for Cuckoo:

adj.

crazy (adjective)
screwball.

n.

childish, crank, crazy, eccentric, kook, laughable, loony, ludicrous, lunatic, nut, over-the-top, ridiculous, screwball, weirdie, weirdo, wise, crackpot, dingbat, ding-a-ling, not in your right mind/not right in the head. bantam, bird of paradise, budgerigar, budgie, bobwhite, bluejay. birdsong, cock-a-doodle-doo, shriek, song. bird (noun)
albatross, bald eagle, barn owl, bird, bittern, blackbird, blue jay, bluebill, bluebird, booby, bullfinch, buzzard, Canada Goose, canary, cardinal, cassowary, chickadee, cockatoo, condor, coot, cormorant, crane, crow, curlew, dodo, dove, duck, eagle, egret, emu, falcon, finch, flamingo, goldfinch, goose, grackle, grosbeak, grouse, gull, harrier, hawk, heron, horned owl, hummingbird, ibis, jackdaw, jay, kingfisher, lark, loon, lovebird, macaw, magpie, mallard, mockingbird, mourning dove, myna, nightingale, nuthatch, oriole, osprey, ostrich, owl, parakeet, parrot, partridge, peacock, pelican, penguin, peregrine, pheasant, pigeon, plover, puffin, quetzal, raven, redbird, redwing, ringtail, road runner, robin, rook, sandpiper, sea gull, sheldrake, snipe, songbird, sparrow, spoonbill, squab, starling, stork, swan, swift, teal, tern, thrush, turkey, turtledove, vulture, waxwing, weaver, woodpecker, wren, yellowbird, crested jay.
cuckoo (noun)
bozo, fathead, goof, goose, twat, zany.
ululation (noun)
bark, bawl, bay, bellow, bleat, bray, cackle, call, caw, chatter, chirp, cluck, coo, crow, cry, gobble, growl, grunt, honk, hoot, howl, meow, mew, moo, neigh, purr, quack, roar, snarl, snort, squawk, squeal, trill, twit, ululation, warble, whinny, yelp.

v.

ululate (verb)
bark, bawl, bay, bellow, bleat, bray, cackle, call, caw, chatter, chirp, cluck, coo, cry, gobble, growl, grunt, honk, hoot, howl, meow, mew, moo, neigh, purr, quack, roar, snarl, snort, squawk, squeal, trill, twit, ululate, warble, whinny, yelp.

Other synonyms:

birdsong, cock-a-doodle-doo, screwball, weirdie, weirdo, crackpot, dingbat, ding-a-ling. crazy, loony, lunatic. shriek, song. crank, nut. eccentric
kook.
Other relevant words:
bozo, childish, cock-a-doodle-doo, crank, crazy, eccentric, fathead, goof, kook, laughable, loony, ludicrous, lunatic, nut, ridiculous, screwball, song, twat, weirdie, weirdo, zany, crackpot, dingbat, ding-a-ling.

Usage examples for cuckoo

  1. Who ever saw a cuckoo when it's talking? – A Prisoner in Fairyland by Algernon Blackwood
  2. " No one can keep me if I want to go," and the old cuckoo clock outside seemed to tick in reply: " Can no one keep her if she wants to go?" – The Captives by Hugh Walpole
  3. Oh, the cuckoo Christina, isn't it a sound that makes one think of tears and happiness!" – The Nest, The White Pagoda, The Suicide, A Forsaken Temple, Miss Jones and The Masterpiece by Anne Douglas Sedgwick