- [usually singular]
a law or an agreement that still exists but that is ignored 无人遵守的法律；形同虚设的协定；空文 The treaty had been a dead letter for many years. 该条约多年来是一纸空文。
- (especially North American English)
a letter that cannot be delivered to an address or to the person who sent it 死信；无法投递（或退回）的邮件