unbutton
/ˌʌnˈbʌtən/verb
with obj.
1- unfasten the buttons of (a garment)解开纽扣。
1.1
- no obj. informal relax and become less inhibited〈非正式〉无拘无束; 放松：
unbutton a little, Molly.
莫莉, 放松点！