English noun: dead letter | |||
| 1. | dead letter (state) the state of something that has outlived its relevance | ||
| Synonyms | non-issue | ||
| Broader (hypernym) | state | ||
| 2. | dead letter (communication) mail that can neither be delivered nor returned | ||
| Synonyms | dead mail | ||
| Broader (hypernym) | letter, missive | ||