I have a group/society of characters that rename themselves goofy "super hero" like names, I guess you'd call it, but there is some rhyme and reason to it. It generally follows the rule of adjective + noun, but the combination gives it a new meaning, but isn't a "compound word". For example, a Dark Horse is someone who unexpectedly succeeds, and White Lightning is a term for illegally made booze (and he's a drunkard in the story, hee). More examples would be Night Owl, Blue Moon, Lone Wolf, ect. There are a lot of color and animal (and colored animals...) names, so I'm trying to avoid those.
Suggestions would be peachy, but just knowing the term for words like that would allow me to search for more, if there is a term. I feel like there ought to be, but I can't think of it. =P
Edit: To prevent comment spam, I'll just edit it here. Thanks a lot for the suggestions so far. ^^ There are some really good ones I'm going to use. You guys rock.