Here are some guidelines you can use to make quick, reasonable decisions about hyphenation.
- When the term appears in the dictionary, use the form in the dictionary.
- Use the guidelines in the style manual for the project. Generally, I use The Chicago Manual of Style, which has a detailed table of hyphenation guidelines available online.
- If there’s no guidance from the dictionary or style manual, apply general guidelines to make a
choice and enter it in the project style sheet so it gets applied consistently. The most basic rules of thumb are as follows:
- Compound modifiers before a noun are usually hyphenated (“full-length section”) before but not after the noun (“the section is full length”).
- Adverbs ending in -ly usually don’t need a hyphen (“a smartly dressed person”) because there’s no ambiguity.
When you’re making decisions about hyphenation, try to avoid getting bogged down on the “logic” or “rightness” of one choice over another. Let your goal be to avoid ambiguity and avoid distracting your reader with unusual formations.
*In the case of literary fiction written by experts, of course, just about anything goes. There’s really nothing wrong with “violetpurple”; it’s not ambiguous or unclear. I find it surprising and therefore distracting, but I expect that the author considers it the most straightforward way of writing what he means, and that’s fair enough.