# file off the serial numbers

idiom

Source: https://englishreference.com/idiom/file-off-the-serial-numbers
Updated: 2026-08-10

## Meaning

To alter identifiable details in a creative work in order to conceal its origin.

## Examples

- The author filed off the serial numbers to hide the story's true origin.
- She files off the serial numbers to make her old blog posts look new.
- To avoid a copyright lawsuit, the writer filed off the serial numbers of the famous characters and renamed them.
- If you want to sell your fan fiction as a novel, you must file off the serial numbers so readers do not recognize the original movie characters.
- The screenwriter filed off the serial numbers from his rejected script and moved the setting from outer space to a historical pirate ship.
- By filing off the serial numbers of the original source material, the developer successfully transformed a fan-fiction project into an entirely original commercial game.

## Origin

The phrase originates from the practice of physically removing a firearm's identification marks to obscure its history. By filing the serial numbers off the metal, a person made the origin and ownership of the weapon difficult for authorities to trace, a procedure generally undertaken to ensure the object's previous life remained a matter of private record.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.