Word forms: plural, 3rd person singular present tense knuckles, present participle knuckling, past tense, past participle knuckled
N-COUNT 指节;指关节 Your knuckles are the rounded pieces of bone that form lumps on your hands where your fingers join your hands, and where your fingers bend. a rap on the knuckles→see: rap指节;指关节
Brenda's knuckles were white as she gripped the arms of the chair.