involuntary adjective
an involuntary movement, etc. is made suddenly, without you intending it or being able to control it 无意识的；不自觉的
an involuntary cry of pain
不由自主的痛苦的喊叫
adverb /ɪnˈvɑː.lən.ter.əl.i/
in a way that is not willing, intentional, or by choice:
Many nurses said they needed to work overtime, sometimes involuntarily.
Arthur shivered involuntarily as he came out of the building.