grumble

US /ˈɡrʌm.bəl/
UK /ˈɡrʌm.bəl/
1.

càu nhàu

to complain about someone or something in an annoyed way:

:
She spent the evening grumbling to me about her job.
1.

càu nhàu

a complaint:

:
When the teacher assigned extra homework, she heard a few grumbles from the kids.