http://www.phon.ucl.ac.uk/home/dick/tta/gloss... says:
A hyphen is sometimes used to join the two parts of a compound noun, as in golf-ball and proof-read. But it is much more usual for such compounds to be written as single words (eg football, headache, bedroom) or as separate words without a hyphen (golf ball, stomach ache, dining room, city centre).

However, hyphens are used in the following cases:

a. in compound adjectives and longer phrases used as modifiers before nouns:

a foul-smelling substance
...

b. in many compound nouns where the second part is a short word like in, off, up or by:

a break-in
a write-off
a mix-up
a passer-by

c. in many words beginning with the prefixes co-, non- and ex-:

co-operate
non-existent
ex-husband

see also: http://phrases.shu.ac.uk/bulletin_board/20/me... for a nice history of hyphenation.

I came across this old thread that never seemed to have gotten much discussion and wondered if it might be a good place to start collecting tips on compound nouns in English.

The rules about compound adjectives are relatively straightforward: write the phrase open after the verb (a boy who is ten years old), but use a hyphen in a compound adjective before a noun (a ten-year-old boy), unless the compound is so familiar that the hyphen isn't needed for clarity (a high school teacher).

But it really is probably harder for learners to predict which nouns are written as one word (closed) and which as two words (open). The question came up not too long ago and we collected some examples here:

related discussion: warum living room getrennt, aber bedroom zusammen?

Then today I was wondering why the code name 'Yewtree' for a police investigation in the UK was written as one word.

related discussion: Yewtree 6 (Jimmy Savile case)

Surely BE speakers don't write *yewtree in other contexts, or *oaktree, *elmtree, *firtree? All the figurative compounds I can think of with tree are open as well: shoe tree, family tree ...

And here's another fairly recent example of an incorrect one-word form:

related discussion: flashflood

But with other words, it's not as clear. We've certainly talked in the past about compounds that are changing even as we speak, gradually coming to be written as one word. These often have to do with technology becoming more familiar: web site becomes website, home page becomes homepage, etc. But then there are others that remain open: search engine, internet browser, others that have long been fixed as one word: database, spreadsheet, and still others where two or more forms are used without a clear trend toward one or the other.

Is it partly just that one-syllable words are more likely to form closed compounds? Or are there other tendencies (calling them rules might be too optimistic) that could help learners predict spelling?

There are some predictable AE/BE differences, though perhaps not as many as there used to be. In the original post from so long ago, for example, ice-cream and dare-devil look either BE or outdated to me. Is it just my impression, or do some of the Oxford dictionaries seem to retain this kind of hyphen longer than the majority of BE speakers? But there are also some that are still in use in BE and thus look quaint only from the perspective of AE.

In #1 above, the prefixes co- and non-, for example, are hyphenated in BE, but usually not in AE. Another group I'm aware of are compass directions: north-west BE vs. northwest AE.

So is anyone else interested in collecting more categories or examples? Or have we already done this before, and if so, could anyone link to the right thread(s)?

Paar lange Wörter suche, ohne daraus eine Regel zu erfinden:

He had a hangover and for her it was a hardship,
although there was no battleship around,
only the normal household garbage,
while all of this results in the ever famous no-nonsense situation, once and for ever.

(Hihi, no-nonsense Situation schreibt man auch auf Deutsch auseinander, Win-win-Situation zusammen!)
- once and for ever/once and forever googelt 3000000 zu 350000, crazy!
- glaub, ever-famous geht auch