An addictive drug,such as opium,that reduces pain,alters mood and behavior,and usually induces sleep or stupor. Natural and synthetic narcotics are used in medicine to control pain.

• 麻醉剂，一种能使人上瘾的药剂，如鸦片，能够减轻疼痛，改变心情和行为，通常导致沉睡或麻木。天然和合成的麻醉剂用于医药止痛。