From Longman Dictionary of Contemporary Englishknuckleknuck‧le1 /ˈnʌkəl/ noun [countable] 1 HBHyour knuckles are the joints in your fingers, including the ones where your fingers join your hands Her knuckles whitened as she gripped the gun.2 DFa piece of meat around the lowest leg joint of a pig a knuckle of pork3 → near the knuckle → a rap on/over the knuckles at rap1(6), → rap somebody on/over the knuckles at rap2(5)
Examples from the Corpus
knuckle• Lee sat reading, folded over the book, chewing a knuckle now.• I clapped my gloves together, surprised when my bare knuckles smacked each other.• Beside them both, Cheryl Russell was sucking her bloodied knuckles.• Susan saw a smear of yellow paint across his knuckles.• He sighed a lot, stretched his legs, cracked his knuckles.• Karma Rubbish smokes at the end of the garden, cracking its knuckles to pass the time.• My consciousness was raised, my knuckles were rapped and I no longer write or think that way.• The power of the punch is concentrated in a small area of the knuckles.knuckleknuckle2 verb → knuckle down → knuckle under→ See Verb tableExamples from the Corpus
knuckle• But he kept his anger under control and vowed to knuckle down and fight for a first-team future.• No attempts made to knuckle down and smarten up.• Male speaker I think we've got to knuckle down and work hard.• Social workers and their managers are clearly ready to knuckle down to the task of making the policy work for users.• Mollified, if not entirely convinced, Vincent went back to Mauve and tried hard to knuckle down.• Some coaches knuckle under to that.Origin knuckle1 (1300-1400) Middle Low German knökel “small bone, knuckle” 