While I was at school, someone told me I can't write for example "superstar", that the correct way is "super star". Is this true?
These days it's best just to look it up online or in a modern dictionary and see what the rule is. In the past hyphens were used a lot, but I'm pretty sure the general thing now is just to cram words together. Really, though, treat them like any word you're not sure of the spelling, and look it up. Modern dictionaries have more than enough slang in to have you covered, and will probably be more reliable than the internet, depending which dictionary source you use, and if it is outdated/relies on users to update it.
in today's usage, only 'superstar' would make sense to readers... so i agree you need to check a modern dictionary, when in doubt...
Yes, I'd just check the dictionary, and see what the spell checker says as well. If both joined and seperated are acceptable, I'd choose one and be consistent. Here's a question - when nouns modify each other, when are they hypenated? I've wondered when making up names for things.
Also be aware that a joined word can mean something different than the separated version. For example "hotbed" and "hot bed" do not mean the same thing.
Also, some authors join two words for artistic effect, creating a "word" that isn't really a word at all but conveys a certain sense to a reader. Even is "superstar" were never joined in actual use, there's no reason you couldn't use it to good effect in a story.
I can tell you that in this example "superstar" is the correct form, if you're talking about someone who has great popular appeal. If you're talking about a brilliant star in the night sky, such as Rigel, the brightest star in the Orion constellation; then "super star" would be correct.
