grumblingгерундий или причастие настоящего времени Functions as a present participle adjective derived from the verb 'grumble'.
Переводы
The grumbling old man complained about the noise.
Ворчливый старик жаловался на шум.
Определения
Complaining or expressing dissatisfaction in a low, muttering voice. The grumbling employees gathered in the break room to discuss their grievances about the new policy.
Emitting a low, continuous rumbling sound. He clutched his grumbling stomach as lunchtime approached.