knuckle noun

ADJ. bony | bleeding, bloodied, bruised, grazed, swollen

VERB + KNUCKLE crack He rubbed his hands together, cracking his knuckles as he tried to control his anger. | bruise, graze, scrape, skin

KNUCKLE + NOUN bone

PHRASES rap sb on/over the knuckles (figurative) The Assistant Manager was rapped over the knuckles for criticizing the company in the press.