or DF

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direction finding.
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Question 1 of 7
Which sentence is correct?

Other definitions for D/F (2 of 3)


Defender of the Faith.

Origin of D.F.

From New Latin Dēfēnsor Fidēī

Other definitions for D/F (3 of 3)


Distrito Federal.
Doctor of Forestry.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does df mean?

The abbreviation df has several meanings and spellings.

D/F stands for direction finding, the process of identifying and tracking radio waves, or direction finder, a tool used to conduct this process. It may also be spelled DF and a direction finder may also be called a radio direction finder (RFD).

DF stands for Distrito Federal, which translates to Federal District in English. DF is the administrative district for Mexico and is part of Mexico City, which extends beyond the borders of Distrito Federal.

DF also stands for Defender of the Faith, a title given to Henry VIII by Pope Leo X in the 1500s and that is still used as a title for British monarchs today.

In dentistry, DF commonly stands for decayed and filled, referring to a tooth that has already been treated for cavities or other flaws. It is sometimes spelled df instead.

DF may also be spelled D.F.

Example: On our recent trip to Mexico, we toured the DF and the rest of Mexico City.

Where does df come from?

The first records of D/F come from around the 1920s, and the first records of the term Defender of the Faith come from around the 1520s.

DF is also an abbreviation for disk free, with disk referring to a storage drive for a computer and free referring to the space available on that drive. It is most notably used as a command for Linux or Unix operating systems.

Abbreviations can be used in both speech and writing, and you may find df in both. In more formal writing, it is common to use the spelled-out form first and use the abbreviation afterwards, ensuring the reader knows what the abbreviation means.

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What are some other forms related to df?

  • D/F (noun)
  • D.F. (alternate spelling)
  • DF (alternate spelling)

What are some words that often get used in discussing df?

How is df used in real life?

DF is an abbreviation used for many terms in different subject areas. In casual speech, it is commonly used to refer to either a federal district or a computer command.

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True or False?

DF can only be spelled one way.

How to use D/F in a sentence

British Dictionary definitions for D/F (1 of 2)


abbreviation for
Defender of the Faith

British Dictionary definitions for D/F (2 of 2)



/ telecomm /

abbreviation for
direction finder
direction finding
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012