dead letter

American  

noun

1. a law, ordinance, etc., that has lost its force but has not been formally repealed or abolished.

2. 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.

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dead letter British  

noun

1. a letter that cannot be delivered or returned because it lacks adequate directions

2. a law or ordinance that is no longer enforced but has not been formally repealed

3. informal anything considered no longer worthy of consideration

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dead letter Idioms  

1. 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]

2. 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]

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Other Word Forms

• dead-letter
  adjective

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Etymology

Origin of dead letter

First recorded in 1570–80

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Example Sentences

See Examples For:

dead letter

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

And she essentially says that this has been a set of cases that ended Wednesday with what she describes as a kind of dead letter, a ghost of whatever Section 2 was.

From Slate ● Apr. 30, 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

The reform of the penny post was soon followed by that of the dead letter office.

From The History of the Post Office From Its Establishment Down to 1836 by Herbert Joyce

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