plural cuckoos
: a type of bird that lays its eggs in the nests of other birds and that has a call that sounds like its name
informal + old-fashioned
1
: silly or crazy
They told me that he's a little cuckoo. [=nutty]
a cuckoo idea
2
: very enthusiastic
I'm not cuckoo [=(more commonly) wild, crazy] about the idea.
Cite this Entry
“Cuckoo.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/cuckoo. Accessed 29 Apr. 2026.
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