Another in our series of Adventures in AP Style. There are some AP style rules that you pick up pretty quickly as a writer. Before long, you can’t really remember if you spell or write something a certain way because it is AP Style, or if it is just grammatically correct.
Today’s case is the phrase "in depth" which many spellcheckers will offer up as either in depth or as in-depth depending upon the program. Some programs, like Windows Live Writer where I’m writing this post right now, suggest both versions!
As a professional writer, I’ve been typing in-depth for so long that I couldn’t remember why. Typically, there is no issue, because a publisher or editor will generally change something like that around to whatever they prefer as part of the editing process. However, this week, I got an email from a client asking me why I used in-depth and whether or not they should switch to it.
When you get a question like this, you not only want to answer correctly, you want to have an authoritative resource you can cite to back you up. In this case, I reached for my AP Stylebook because it sits on a shelf less than a foot away (and it’s smaller than the dictionary) and found it right away under the listing for in- as a prefix as one of the occasions that AP Style mandates as always requiring a hyphen.
The rest of the rule, if you are curious, is that in as a prefix does not take a hyphen when it means "not" and in incapable, inconsiderate, or incompetent.
That means that while you are writing your way through the world, assume that there is no need for a hyphen when using a word that has in as a prefix unless that prefix has a meaning other than "not" as in in-depth.