involuntary
US /ɪnˈvɑː.lən.ter.i/
UK /ɪnˈvɑː.lən.ter.i/
1.
không tự nguyện
not done by choice; done unwillingly, or without the decision or intention of the person involved:
:
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A sharp tap on the knee usually causes an involuntary movement of the lower leg.