dead letter
Longman Dictionary of Contemporary English 5++LDOCE 5++ˌdead ˈletter noun [countable] 1. USEFUL#a law, idea etc that still exists but that people no longer obey 形同虚设的法规，空文；名存实亡的观念2. TCMa letter that cannot be delivered or returned 无法投递[退回]的信，死信
Examples from the Corpus
dead letter• The fact that the postwar treaty had been a dead letter for many years did not worry either party.• An arts education is a dead letter for many students.• Theoretical reasoning is a dead letter to the child unless it is closely anchored to practical issues.ˌdead ˈletter nounChineseSyllable
a still etc that idea exists Corpus law,
dead letter
ˌdead ˈletter
noun [countable]
1. a law, idea etc that still exists but that people no longer obey
2. a letter that cannot be delivered or returned
ˌdead ˈletter
noun [countable]1. a law, idea etc that still exists but that people no longer obey
2. a letter that cannot be delivered or returned