Apparently its meaning isn’t really known, but in European folklore [name]Melusine[/name] was a water fairy who turned into a serpent from the waist down every [name]Saturday[/name].
Ha! I wrote a paper on the French version of this book in grad school. Yes, she was cursed, and her punishment was spending [name]Saturday[/name] as a serpent. She met with a cruel and awful fate. I wouldn’t suggest it as a usable name anywhere except literature. It’s pronounced mehl-oo-ZEEN.
I actually really like [name]Melusine[/name]; it was hovering around my Top 20 for a good long time. Then I read a godawful fantasy book called [name]Melusine[/name] by [name]Sara[/name] Monette, which spoiled the name utterly. Such a shame. (There wasn’t even a melusine in it!)