A complicated involuntary reaction to a sudden unexpected stimulus (especially a loud noise),involves flexion of most skeletal muscles and a variety of visceral reactions.

• 对突然出现的、意外的刺激（尤其是巨大的声响）做出的一种复杂的、无意识的反应，伴随有大多数骨骼肌肉的弯曲和各种内脏反应。