I always see the letters Dx as the abbreviation of diagnosis, but I never understand how does this letter relate to the word diagnosis which doesn't contain the letter x. Therefore my question is

What do these two letters (Dx) stand for?

An example using these letters: Dx: atrial fibrilation and right bundlebranch block. (in cardiology)


3 Answers 3


There are a number of abbreviations which use the first letter and an 'x'. The other ones I can think of are:

Rx - Latin recipe ("take" - the traditional first word of a recipe!)

Tx - transmit/transmission

Rx - receive/reception

I suspect that the practice goes back to scribal abbreviations, though I don't know for sure.

  • 1
    Here are some more: englishforums.com/English/OnGroundThoseAbbreviationsCreated/…
    – sumelic
    Commented Mar 6, 2016 at 23:43
  • I think a lot of the replies on that forum are unsupported speculation, and probably wrong.
    – Colin Fine
    Commented Mar 7, 2016 at 0:01
  • Probably! I didn't know about "Sx," "Fx" etc though.
    – sumelic
    Commented Mar 7, 2016 at 0:03
  • No, I didn't, either. It is noticeable that all the examples we have are used in particular fields, effectively as professional jargon: I'm not sure that any of them will be understood by the general public, except possible Rx for a prescription.
    – Colin Fine
    Commented Mar 7, 2016 at 0:14
  • 1
    Good information but it doesn't answer the question.
    – user3169
    Commented Mar 7, 2016 at 0:46

Dx is an abbreviation for a medical diagnosis or diagnostic (tool).

If you Google search on Dx diagnostics you can find numerous references.

dx is also used in radio communications, but that meaning is different (included in the above definition).


It comes from the manuscript practice of adding a crossbar to a letter to indicate that it's an abbreviation, like with Rx, the diagonal of the R was extended downward and crossed, so that it resembled a ligature of R and x. As typesetting was introduced, the lower-case x was a convenient way to represent such abbreviations.

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