Some compound words are separated by a space (e.g. ice cream). Others are simply joined together (e.g. football, doorknob). Others still are hyphenated (e.g. long-term, off-topic).

Why is the handling of compound words not entirely consistent? What determines whether a new word will be spaced, joined, or hyphenated?

  • 1
    New words are generally spaced. After being used for a while, they are often either joined or hyphenated. See Google Ngrams for door?knob. Commented Nov 7, 2022 at 17:43
  • FYI the hyphen in long-term and off-topic serves a special purpose in a special situation. A time period could span a long term, and I could be riffing off topic of the day to say so. Commented Nov 7, 2022 at 17:55
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    Users determine everything in English. In fact, English is an anarchist's dream. [ha ha] If someone decides to start using off topic without a hyphen to be an adjective, it's their business since there is no big hand in the sky that will come down and grab them. That said, you do get things like: This is off topic. Versus: We discussed no off-topic matters.
    – Lambie
    Commented Nov 7, 2022 at 19:25
  • With only a few exceptions, if the two words are spaced, they do not form a compound word (two bases) but a syntactic construction (head +modifier). "Ice-cream" passes all the tests for compoundhood and thus should be written as a single word, hyphenated.
    – BillJ
    Commented Nov 7, 2022 at 19:39
  • At least very closely related: When should compound words be written as one word with hyphens .... There are some reasons involved, but the fact that many words' spelling evolves from open compound to hyphenated form to closed form, usually faster in the US than the UK, and often with acceptable alternative options, indicates that idiosyncrasy is involved. Commented Nov 7, 2022 at 19:43

1 Answer 1


Consistency of the form is not at stake: you might however speak of lack of consistency in the spelling of compound words. The reason why there is not a uniform way of spelling them is that there were no directives as they started being used in hyphenated form or closed form, so people coining or using them might use one of the three forms rather than another.

Hyphenation as a compounding technique in English Nonetheless, hyphenated compounds have largely been ignored in the academic literature. Likely because of the common belief that using hyphenation to link words (such as punctuation practices) tends to be conventional (i.e., just a matter of spelling), only a few studies have explored hyphenated compounds, such as Mondorf (2009) and Kuperman and Bertram (2013).

As time went by, there has been much evolution and finally some compound words can be found for which the three forms can be considered correct.

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Notice the great number of cases found for the apparently rare icecream, which is in fact only relatively rare.

The contemporary trend in spelling compound words would be to use hyphens more, but this question is quite complex as hyphens also tend to disappear (economy of writing, such as promoted by typing, for instance); see the article shown above (Hyphenation as a compounding technique in English) if curious enough about this evolution in English spelling: although not easy to follow this masterly study still provides much insight accessible to the layperson.

There is also a difference according to what variety of the language you consider.

(CoGEL III 4, Quirk et al., 1985) AmE inclines to fewer hyphens than BrE, preferring words to be written either open (separated by a space) several exceptions:either OPEN by a space) or SOLID (without separation) rather than hyphenated.

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