I (myself) prefer one but an editor I use redlines it as a misspelling, so which one should we use here?

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    $\begingroup$ You don't need quora, only a dictionary dictionary.cambridge.org/dictionary/english/redshift $\endgroup$
    – James K
    Commented Jan 31 at 5:50
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    $\begingroup$ I think it's rather normal for the English language, when two nouns are combined to form a new noun, to start out separated, then hyphenated, and finally conjoined. In addition to "red shift → red-shift → redshift", examples include "light year → light-year → lightyear", and also "minutes of arc → arc minute → arc-minute → arcmin", I think. "Light-seconds" are still hyphenated though, perhaps because it's not as popular a word. $\endgroup$
    – pela
    Commented Jan 31 at 11:33
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    $\begingroup$ It's your web browser that's doing the spell check, not Stack Exchange or Quora or the ESA website. $\endgroup$
    – notovny
    Commented Jan 31 at 19:02
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    $\begingroup$ I think the question is OK. From time to time we have questions that ask to clarify certain items necessary to write or publish about Astronomy. See for example How is the star 'Spica' pronounced? and When we say a variable star is "fainting" does it mean something more or different than "dimming" or "fading"? At only 3.6 questions per day, it's not like we're so overwhelmed that we need to split hairs on topicality. After all, this has a well-defined, and it turns out interesting answer! $\endgroup$
    – uhoh
    Commented Feb 1 at 7:22
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    $\begingroup$ And that answer is fact-based, so closing for "This question is likely to be answered with opinions rather than facts " seems pointless. voting to leave open $\endgroup$
    – uhoh
    Commented Feb 1 at 7:25

1 Answer 1


It’s a single word. Used to be double, but quickly became single.





https://books.google.com/ngrams/graph?content=redshift%2C+red-shift&year_start=1800&year_end=2019&corpus=en-2019&smoothing=3 (I’d curious about the diminishing number of mentions of “redshift” since 2000—not that “red-shift” has increased during the same period, on the contrary)

  • $\begingroup$ But then why does this editor and Quora's too redline it, as a misspelling? Wot, it's/they're out of date? $\endgroup$ Commented Jan 31 at 7:57
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    $\begingroup$ Scientific terms very often get redlined by non-scientific spell checkers. I've also had spell checkers ping on "email" because they think it should have a hyphen. Language evolves and programs react slowly. $\endgroup$ Commented Jan 31 at 15:00

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