If you make an involuntary movement or exclamation, you make it suddenly and without intending to because you are unable to control yourself.
例句
Another surge of pain in my ankle caused me to give an involuntary shudder.腳踝突然又一陣疼痛，痛得我直打哆嗦。
ADJ
強迫的;非自愿的
You use involuntary to describe an action or situation which is forced on someone.
例句
...insurance policies that cover involuntary unemployment...涵蓋非自愿失業的保險單Involuntary repatriation of Haitians began this week.這周已開始將海地人強制遣送回國。
英漢詞典釋義
adv.
不由自主地;本能地
Her eyes strayed involuntarily.她的目光不由自主地移開了。Her hands clenched involuntarily.她本能地攥緊了拳頭。She shivered involuntarily as he approached her.他離她越來越近，她不由自主地顫抖起來。