1HBDELIBERATELYan involuntary movement, sound, reaction etc is one that you make suddenly and without intending to because you cannot control yourself 〔动作、声音、反应等〕无意识做出的,非故意的
When Willie tapped on the window, Miguel gave an involuntary jump.
威利敲了敲窗户,米格尔不由自主地跳了起来。
2happening to you although you do not want it to 非自愿的