I work with electronic circuits terminology a lot and I sometimes see key switch (two words) and keyswitch (one word). I was wondering which one is right ?

The word is to designate a switch activated by a physical key that has to be inserted.

e.g. Elevator override keyswitch/key switch located at the main floor.

  • It may depend on the context, or could be just random people spelling it different ways.
    – Robusto
    Jan 9, 2015 at 14:29
  • Logically, it should be one word. However, until the "word" is recognized and documented (in some authentic document somewhere), it may be necessary to use the phrase, maybe with a hyphen for the time being: key-switch HTH.
    – Kris
    Jan 9, 2015 at 15:01
  • @Kris how so should above? Also the querent reports that they can attest for its use themselves.
    – Jon Hanna
    Jan 9, 2015 at 15:06
  • This "Idiots Guide to Components of Electrical Circuits" says The switch or key helps to make or break the circuit, i.e. switches on or switches off the current. I'm not an electronics engineer, but it seems to me for the sense under consideration most instances where both words are used (fused into a single word, hyphenated, or two separate words) are actually from Far Eastern scientists not writing in their native language. Jan 9, 2015 at 15:12
  • @FumbleFingers there's plenty of cases where other uses of keyswitch or key switch could be confusable with the sort you'd have for an elevator override, but I don't think that link shows one of them.
    – Jon Hanna
    Jan 9, 2015 at 15:17

1 Answer 1


It's a compound, and often compounds can exist in different people's use, between open (key switch), closed (keyswitch) and hyphenated (key-switch).

Generally compounds start out open or hyphenated (note also, in many people's use it might be open when used as a noun and hyphenated when used as a modifier, so someone who said "protected by a key switch" might say "key-switch protection") and if they're used a lot then more and more people will start using them closed and they'll "become a word".

But they can also co-exist in two forms for a long time, or even three (egg-beater, egg beater and eggbeater have been each going for some time).

So, if more than a handful of people are using a particular form, then it's reasonable to consider it a correct form, but not necessarily the correct form.

Your own question points out that both key switch and keyswitch are in use, and suggests that they're both in enough use that both could be considered correct.

We can try some surveying, though I hasten to add that there are a lot of caveats with this source:

This shows key-switch not being used a lot, and we can imagine that it actually overestimates the number due to what I mentioned above about people hyphenating some open compounds when they are modifiers.

It shows key switch being much more commonly used than keyswitch.

This is also quite likely overestimating keyswitch here because keyswitch is also used for a type of switch that is used to make keyboards. The fact that this sort of keyboard design is less common now and keyswitch has declined toward the end of the 1990s backs this theory up.

It may though also overestimate key switch too, because the combination could occur in wider phrases with different meanings. So we aren't conclusive yet.

So we look through results for both term and see which are more often in use. Again while we find keyswitch and key switch both in use for this sort of term, we find the latter considerably more often than the former (discounting other uses of either). Not a massive survey of the language, but enough to be reasonably confident key switch is definitely getting considerable use here.

And as such we can conclude that key switch is much more often used than keyswitch in this context.

It's enough to give us confidence that key switch is certainly correct. Whether we can conclude that keyswitch is incorrect or also correct but less popular requires both more dependable data than this and a consensus on when an English word can be considered "correct" that we are never going to see.

But we can conclude that unless you really, really just like keyswitch better, it might be a good idea to use key switch but not complain about anyone who uses keyswitch either.

  • 1
    There is a problem with the statistic for the expression "key switch", because that combination can easily occur in sentences that have nothing to do with the OP's hardware. For instance: "The key switch that enabled Team A's win on Saturday was replacing the injury-prone Player X with Player Y as a striker". Clearly, many false positives could be generated by such uses of the term.
    – Erik Kowal
    Jan 9, 2015 at 15:07
  • @ErikKowal thanks. I thought I'd covered the issues with the results for all three terms, but I did indeed skip those for that one.
    – Jon Hanna
    Jan 9, 2015 at 15:15

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