an automatic instinctive unlearned reaction to a stimulus
双语例句
Laughter is beneficial for human health, it is one kind of complex nerve reflex action. 笑对于人体健康是有益的，它是一种复杂的神经反射作用。
This produces in turn a reflex which brings about a disturbed elimination with consequent constipation. 这反过来会产生一种反射作用，这种作用引起排泄紊乱接着引起便秘。
After all, a reflex reaction to a poke in the eye does not necessarily mean that eyes had evolved to perceive sudden jabs. 毕竟，眼睛被戳到而引起的反射动作，不表示眼睛是演化来感觉快速直拳的。
