dead-letter dead-leaf • dead-live · · · Info · Definitions · Synonyms · Characters · · dead-letter · · Text Common · · Latin · · Scripts 11 · · Length Definitions · · · (noun) the state of something that has outlived its relevance. Synonyms: dead letter, non-issue. · · Noun Definition 1 (noun) mail that can neither be delivered nor returned. Synonyms: dead letter, dead mail. · · Noun Definition 2 Synonyms · · · dead letter · · Synonym 1 non-issue · · Synonym 2 dead mail · · Synonym 3 Characters · · - hyphen-minus U+002D a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 l latin small letter l U+006C r latin small letter r U+0072 t latin small letter t U+0074