This is the 6559th most frequent Chinese word.
无效
Invalid; ineffective.
无效 is used to express that something fails to produce the desired effect or result.
该药物对他的病情无效。
This medication is ineffective for his condition.
无效 indicates the state of being invalid or void.
这个优惠券已经无效了。
This coupon is no longer valid.
无效 is used to denote an unsuccessful operation or action.