collet
/ˈkɒlɪt/noun
1- a ring or lining that holds something, in particular抓握东西的环形物（或环衬）, 尤指：
1.1
- a segmented band or sleeve put round a shaft or spindle and tightened so as to grip it有缝套爪。
1.2
- a small collar in a clock to which the inner end of a balance spring is attached（时钟内）钩住发条的金属箍环。
1.3
- a flange or socket for setting a gem in jewellery（珠宝上）镶嵌宝石的底座。
词源
late Middle English (denoting a piece of armour to protect the neck)： from Old French, diminutive of col 'neck', from Latin collum.