Copy editor or copyeditor?

If you're a natural born one of the above, you may have noticed I wrote "copy editor" as two words in the previous post. However, in my profile I spell it "copyeditor. " Which is it, and why wasn't I consistent? The answer is that it can be spelled either way, as can "copy editing" and "copyediting." I prefer it as one word and use it that way in this blog and on my website. But since I was quoting directly from Cheryl Klein and she had used it as two words, I thought it appropriate to keep it that way.

My favorite book on the subject is Copyediting: A Practical Guide by Karen Judd.