扣

On the HSK 6 vocabulary list, at CEFR level C2.

kòu ㄎㄡˋ

扣
- to fasten
扣
- to button
扣
- button
扣
- buckle
扣
- knot
扣
- to arrest
扣
- to confiscate
扣
- to deduct (money)
扣
- discount
扣
- to knock
扣
- to smash, spike or dunk (a ball)
扣
- to cover (with a bowl etc)
扣
- to tag a label on sb
  fig.
扣
- (loanword) code
  Tw
釦
- button

Sources