knuckle has definitions from the fields of anatomy,sport
1
[ noun ] (anatomy) a joint of a finger when the fist is closed

Used in print

(Louis Zara, Dark Rider....)

He was frightened ; his fists clutched so tightly that his knuckles hurt .

(Gerald Green, The Heartless Light....)

They answered him in monosyllables , nods , occasionally muttering in Greek to one another , awaiting the word from Papa , who restlessly cracked his knuckles , anxious to stuff himself into his white Cadillac and burst off to the freeway .

(Sallie Bingham, "Moving Day," The Atlantic...)

Then he looked at his finger , at the wrinkled , heavy knuckle and the thick nail he used like a knife to pry up , slit , and open .

Related terms

joint synovial_joint finger

2
[ verb ] press or rub with the knuckles

Related terms

press

3
[ verb ] (sport) shoot a marble while keeping one's knuckles on the ground

Related terms

shoot

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