dead letter
Americannoun
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a law, ordinance, etc., that has lost its force but has not been formally repealed or abolished.
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a letter that cannot reach the addressee or be returned to the sender, usually because of incorrect address, and that is sent to and handled in a special division or department dead-letteroffice of a general post office.
noun
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a letter that cannot be delivered or returned because it lacks adequate directions
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a law or ordinance that is no longer enforced but has not been formally repealed
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informal anything considered no longer worthy of consideration
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An unclaimed or undelivered letter that is eventually destroyed or returned to the sender. For example, She moved without leaving a forwarding address, so her mail ended up in the dead letter office . [c. 1700]
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A statute or directive that is still valid but in practice is not enforced. For example, The blue laws here are a dead letter; all the stores open on Sundays and holidays . [Second half of 1600s]
Other Word Forms
Etymology
Origin of dead letter
First recorded in 1570–80
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
But on Sunday, the group warned: "Many provisions of the law will remain a dead letter" unless 77-year-old Ocalan, in jail since 1999, was released from prison.
From Barron's ● Aug. 9, 2026
Every day that passes makes that resolution more of a dead letter, and adds to the elusiveness of a deal.
From The Wall Street Journal ● Oct. 23, 2025
This, Kagan says, renders impeachment and conviction virtually a dead letter.
From Salon ● Nov. 18, 2024
"As a result, the YCC framework seems to have become more of a dead letter."
From Reuters ● Oct. 31, 2023
About the same time the dead letter office received most valuable help in the discharge of its duties from the publication of what was, virtually, the first County Directory.
From The History of the Post Office From Its Establishment Down to 1836 by Herbert Joyce
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
