Originally posted by Henry:
My Latin is as rusty as an old gate-hinge, but I believe it's
codex ex spiriti lunae
for a very rough pronunciation guide:
KO-dex ex SPEER-ee-tee LOON-eye
The spirit and the "moon" adjective should both be genitive case. "Of the (moon) spirit."
This is actually incorrect, Henry. You need to use "de" instead of "ex" as the preposition. That's the normal convention for Latin book titles. Also, both de and ex take the ablative, not the genitive (I don't know how much it matters to you, Henry, but you have the genitive for spiritus wrong, too., Spiritus is fourth declension, so the genitive is spiritus, with a long u. You probaly also want to use the adjective form of luna, which is lunaris)
So, taking all that into consideration, you probably want something like this, Tyr:
Liber de spiritu lunari
You probably want liber instead of codex, as liber is the word that means "book" in the abstract sense of a longer, written work, and was the word most often used in titles of this sort. Codex can mean book, too, but usually refers to a book as a physical object. So, unless you want to emphasize that the Book of the Moon Spirit is actually a
book, as in something with a cover, a binding, and a bunch of sheets of paper inside, rather than, say, a collection of scrolls, you should use liber.
Other than that, it's just a matter of using the right preposition and putting the noun and adjective in the right case.
drquestion
edit: Henry beat me to it, so I added a response to him