I can't seem to spot any differences or usages where one would use the hyphenation version versus the non.
According to Online Etymology they both point to coordinate.
I can see co-ordinate (v.) being used like co-pilot or co-chief, meaning a daulity or partner version. Example: Would you please co-ordinate with Bob. Meaning Bob is already ordinating and if you would also ordinate with him.
Yet I don't see that transferring over to the noun version meaning a location, especially in reference to mathematics and geography.
Is it simply a mix-up, or perhaps a localization issue (UK uses -, USA doesn't) or am I completely off base here?
Best Answer
Making a quick search in my NOAD, it seems they are the same exact term.
But, like I was thinking, coordinate is the term used, since if you search for co-ordinate, it will redirect you to the other one.
Look what happens if you search for co-ordinate in the OALD.
If you type them in Google, you'll get the following results:
Quite a difference... In the end I suppose the hyphened version is a variant, you might use either, although nowadays they're not really considered compound words anymore (another similar words is cooperate) but single words.