By Mary Morel
The hyphen has dropped out of coordinate, but co-ordinate is not wrong.
Hyphens tend to drop out over time when words are used together a lot.
e-mail is now email
semi-colon is now semicolon
Use a modern dictionary as your guide.
Read my post on hyphens.
Learn more about punctuation with my online course, An A to Z of Punctuation (A$39).