What is 'coucou' in English?

The Word 'coucou' is translated as cuckoo, in terms of the European bird that gets its eggs hatched in other birds' nests. It's cowslip, in terms of the plant. And it's cuckoo clock, in terms of the charming timepiece whose hour is sounded by a musical cuckoo bird.

Addition by crisdean

Coucou is also a familiar way to say Hi or Hello, it is kind and friendly. Almost used on the internet, on the phone or in spoken french.