- [intransitive] when a dove or a pigeon coos, it makes a soft low sound(鸽子)咕咕叫
More Like This Animal soundsAnimal sounds Topics Birdsc2 - [intransitive, transitive] (+ speech) to say something in a soft quiet voice, especially to somebody you love(尤指对所爱的人)轻柔低语,柔情地说
Word Originverb and noun mid 17th cent.: imitative.
Idioms - (old-fashioned, informal) if two people who are in love bill and coo, they kiss and speak in a loving way to each other卿卿我我;情话绵绵