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Are there any rules when to write a set of two (or more) words or abbreviations forming a name of some entity as separate, when to hyphenate, and when to stick them together?

These are my findings with ngram:

  • bitwise, bit-wise, but never bit wise
  • sci-fi, but never sci fi, or scifi
  • wastelands (increasingly frequent), waste lands (dying out), never waste-lands
  • fanfiction or fan fiction, but almost never fan-fiction, but
  • fanfic, never fan fic or fan-fic
  • read-only or read only, rarely readonly
  • twofold (frequently), two-fold (rarely), two fold (minimal)
  • bittersweet (rise), bitter-sweet (decline), bitter sweet (minimal), but...
  • sour-sweet (frequent), sour sweet (less frequent), soursweet (even less frequent)
  • all-nighter (dominant), allnighter (infrequent), all nighter (somewhat less frequent)
  • cross-country (gaining), crosscountry and cross country (about equal, not infrequent)
  • overnight (rise), over night (same as overnight until 1920, then drops to 0), very rare over-night.

In particular, if I'm coining a new blend, which rules should I follow when deciding which of these three forms to give it?

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The normal progression is from spaced to hyphenated to nothing at all. Now-a-days, to-morrow. Might as well cut to the chance and try it without. – tchrist Dec 2 '12 at 0:26
Don't use a hyphen if the fused combo isn't confusing and doesn't have two vowels (especially identical vowels, e.g., "meta-analysis", "intra-articular", "quasi-isomorphism", "proto-oncogenic") surrounding the hyphen. Sometimes two vowels are okay, though: e.g., "proactive". – user21497 Dec 2 '12 at 7:48
@tchrist: "Cut to the chase" is it not? – user21497 Dec 2 '12 at 7:49
[hyphen] is a tag on ELU. "to hyphen or not to hyphen" returns 55,900 results on Google. See, Simon Rabinovitch: Thousands of hyphens perish as English marches on (OED: Exhaustive research on hyphen sundaytimes.lk/070923/International/international000013.html) – Kris Dec 2 '12 at 8:34
up vote 2 down vote accepted

The rule is that there are no rules. But, there are some general trends....

Before English lost the genitive case, the first noun would have been declined in the genitive to represent that it owns or modifies the second noun. We actually still see some compound words with a remnant of the Old English genitive. For example, the -s- in Doomsday is declining doom into the genitive. That would be the end of the story for that word, but we don't have a genitive case anymore, so things get a little more convoluted.

English has 3 forms for compound words:

  • The open form, where the compound word is separated by a space.
  • The apltly named hyphenated form, where a hyphen is used as the delimeter.
  • The closed form, where the words are merged with no delimeter.

The general trend is that a word starts open, becomes hyphenated, and eventually, the any delimeter that was there is removed to make the closed form.

But as I said, the rules are: There are no rules. There can be any combination of these stages in existence for the same compound word leading many to wonder, which one is more correct?. Stages can also be skipped entirely, starting out hyphenated or going from open form to closed form directly, And, still, there is yet another exception to be made for the common prefixes we have taken from Latin/Greek, those are almost never hyphenated. For example telephone, a recently invented word, was never tele-phone. But even then, there are exceptions. Some of which are mentioned here.

I'm sure a few minutes of thought and more rules can be posited and then more exceptions to those rules found. Your best bet is just to follow the most common spelling of a word on a case-by-case basis. By the time it changes and people start questioning your spelling, you'll be long since dead.

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The general trend is that a word starts open, becomes hyphenated, and eventually, any delimeter that was there is removed to make the closed form. And this process seems to happen more quickly in US than in UK English. Stephen Wilbers at wilbers.com/part224.htm quotes: Your spelling-checker is of little help, so the safest way to deal with this mess is to consult a dictionary ... a smaller paperback. Recycle the paperback every five years to keep abreast of vanishing hyphens in words such as nontraditional and soon-to-vanish hyphens in terms such as e-mail, log-in, and on-line. – Edwin Ashworth Dec 2 '12 at 23:04
@EdwinAshworth Good point! I had not considered that different English dialects might handle this differently. – Sean Cline Dec 2 '12 at 23:22
Interestingly, the article linked by Kris lists quite a few cases where the hyphenated form dies in favor of the open form: fig leaf, hobby horse , ice cream , pin money , pot belly , test tube , water bed. – SF. Dec 3 '12 at 1:11
Yes – I wouldn't fancy any of these as closed forms. Perhaps the rule of thumb (I had to check that!) is 'there is a tendency to drop the hyphens of hyphenated forms – in favour of the closed form where that would not look like it might sound, or otherwise look, peculiar – or the open form otherwise'. – Edwin Ashworth Dec 3 '12 at 9:21

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