knuckle

英 ['nʌk(ə)l] 美 ['nʌkl]

1. knock => knuckle.
2. 我们敲门的时候不正是使用的是指关节去敲门的吗？

knuckle 指节

来自Proto-Germanic*knuk,骨头，-le,小词后缀。引申词义指节，铜指手套（一种过去的武器）。

knuckle: knuckle: [14] Knuckle originally denoted the rounded end of a bone at a joint, which sticks out when you bend the joint. This could be at any joint, including the elbow, the knee and even the joints of the vertebrae; only gradually did it become specialized to the finger joints. The word probably came from Middle Low German knökel (or a relative of it), which appears to have meant etymologically ‘little bone’. Knuckle down, in the sense ‘begin to work hard and conscientiously’, comes from the game of marbles, where players have to put their knuckles on the ground when shooting a marble with the thumb.
knuckle (n.): mid-14c., knokel "finger joint; any joint of the body, especially a knobby one; morbid lump or swelling;" common Germanic (cognates: Middle Low German knökel, Middle Dutch cnockel, German knöchel), literally "little bone," a diminutive of Proto-Germanic root *knuk- "bone" (compare German Knochen "bone).

As a verb from 1740, originally in the game of marbles. To knuckle down "apply oneself earnestly" is 1864 in American English, extended from marbles (putting a knuckle on the ground in assuming the hand position preliminary to shooting); to knuckle under "submit, give in" is first recorded 1740, supposedly from the former more general sense of "knuckle" and here meaning "knee," hence "to kneel." The face-busting knuckle-duster is from 1858 (a duster was a type of protective coat worn by workmen).

1. The United States, he said, did not knuckle under to demands.: 他说，美国不会屈从于他人的要求。

2. David Seaman was back in the Arsenal goal after breaking a knuckle.: 戴维·西曼在一个指关节骨折后又回到阿森纳队的球门前。

4. The only thing to do was knuckle down and get on with some serious hard work.: 唯一能做的就是开始努力工作，好好干出点儿成绩来。

5. He managed to knuckle down to his lessons long enough to pass his examination.: 他在离考试还有足够长时间的时候就开始认真学习，从而通过了考试。