Could I use the following sentence, please:

According to the timeStepDirection value (+1 or -1), change the current program number to or fro along the time axis.

If not, is it at least possible to use such combination in a totally informal sentence?

Or "to and fro" is an absolutely immutable idiom?

Sorry, my example was very bad. Eventually I changed "to or fro" here to "appropriately".

But could such form be used in another context?

  • 1
    Immutable idiom or not, it would certainly not be advisable in your context. The sentence you provided has no room for ambiguity or use of fancy literary devices.
    – Kris
    Feb 14, 2012 at 12:01
  • @Kris And in another context, could you imagine a use of such form?
    – Gangnus
    Feb 14, 2012 at 13:06
  • Google search provides quite a few, mostly unconventional I believe.
    – Kris
    Feb 14, 2012 at 14:40
  • The "fro" is short for "from," so "to or fro" means one trip, one way. Feb 14, 2012 at 16:24
  • @PeteWilson "The pendulum was swinging to and fro" - one trip, of course.
    – Gangnus
    Feb 14, 2012 at 16:27

3 Answers 3


It seems like no one has attempted an answer to the original question, which is whether there is a plausible sentence (informal or not) where "to or fro" could be used as an alternative to "to and fro", even if with a different meaning.

Here's one suggestion:

Each afternoon after school let out, Bobby would run to or fro or wherever the spirit would move him.

To me this seems to be a sort of punning way of saying that Bobby is too scatter-brained to even manage to run back and forth (to and fro), but somehow just ends up jumbling up his movements in such a way that he has at no point any intentional direction of travel at all.


"To and fro" is the idiom, and it implies a movement both ways, and multiple times. If that is not what you need, then this is probably not the right idiom. It is not uncommon to hear it in spoken word repeated - "to and fro, to and fro", which supports the multiple times approach.

If you are asking, as it seems, for a single movement in one direction or the other per iteration, then this is wrong, and using it will confuse your listeners. A simple Up or Down may work better.

  • 1
    The problem is, that one of the most effective ways to make the language alive, is to play with idioms - to change them, or to take some parts from one, some from another. And using humor always supposed some intellectual work of the listener/reader. But I shouldn't play in the strictly technical text, so your variant is much better.
    – Gangnus
    Feb 14, 2012 at 13:02
  • I think there are cases for playing with the idiom, extending it, but not at the same time as trying to use it to communicate in a technical document that this appears to be. Feb 14, 2012 at 16:09

It's not that "to and fro" is an absolutely immutable idiom. The salient point is that "to or fro" would have a different meaning. Thus, one could not use "to or fro" as a substitute for "to and fro". Simply because "or" has a different meaning from "and".

So, suitable substitutes for "to and fro" might be:

"Hither and thither", "here and there", "backwards and forwards".

It will be appreciated that replacing the conjunction "and" with the alternative coordinating conjunction "or" changes the meaning of the utterance accordingly.

  • 1
    I am not asking on substitutes, sorry.
    – Gangnus
    Feb 14, 2012 at 12:59
  • Should read "for substitutes", not "on substitutes". Your question was: Is to and fro an immutable idiom? I illustrated that it is not. Further, I provided synonyms to demonstrate the deeper meaning of to and fro that had evidently heretofore eluded you. Finally, I showed that to say otherwise, e.g. to or fro, is to make a different statement with a different meaning. That was and remains the extent of my engagement in this to and fro, back and forth with you. Feb 14, 2012 at 15:23
  • Thank you. I know what to and fro means. I was interested in the not substitute, but the derivation of this form, namely "to or fro".
    – Gangnus
    Feb 14, 2012 at 16:18

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