Knuckle under vs knuckle down

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Knuckle under and knuckle down are two idioms that are similar but have very different meanings. An idiom is a word, group of words or phrase that has a figurative meaning that is not easily deduced from its literal meaning. We will look at the difference between knuckle under and knuckle down, where the terms came from and some examples of their use in sentences.

Knuckle under means to give in, to submit, to yield. The term knuckle under is an American phrase that was first used in the 1700s. The term knuckle under was most probably an allusion to bending low in submission so that one’s knuckles brushed the ground.

Knuckle down is a phrase which means to get serious about a task, to work diligently on a task or problem. Knuckle down is a term derived from the game of marbles, it first appeared in the mid-1860s in American English. One puts a knuckle to the ground to assume the shooting position in marbles, thus the term knuckle down. Interestingly, in the 1700s the term knuckle down was used to mean to give in, to submit, to yield. For a time both knuckle down and knuckle under meant the same thing, but their meanings diverged in the mid-1800s.


Parris clearly has issues with this characterisation: “What I would have liked it to be is akin to a College tutor, and if some nasty department or individual wrongs you in College, the theory is your tutor takes your defence, even if it was against the College, and does not simply say ‘that’s the college rule, you better knuckle under and put up with it.” (The University Times)

We can either knuckle under, yet again, with a managed trade solution that continues to restrict our lumber exports to the United States, or we can resist new restrictions under various trade tribunals open to us while at the same time accelerating exports to more welcoming Asian markets such as China and Japan. (The Globe and Mail)

You have no choice but to knuckle down and graft else you won’t get an opportunity to showcase your skills on the big platform. (The Birmingham Mail)

There may not have been conventional clear the air talks with the manager but, via a persuasive word in his ear from his team-mates, Costa has been made aware of the need to knuckle down. (The Guardian)