So Leviathan sounds big and scary and intimidating, thus making it an excellent name for a warship, right? That's definitely part of it, but this isn't the first time the word leviathan or a reference to the leviathan makes an appearance in literature. Not by a long shot.
In the Old Testament/Hebrew Bible, the leviathan is a great sea monster. Unlike our friendly flying whale, though, the biblical leviathan is more like a demon or some kind of servant of hell. In popular culture, leviathan has come to mean any ginormous sea monster.
If you're on your political-theory toes, you might recognize Leviathan as the title of Thomas Hobbes's 1660 book on how society and government should work. Is Westerfeld trying to make a statement on how society and government should work in his book? What do you think?
If we're looking at the importance of the airship Leviathan to the book though, we have to say it deserves the title role because it's what brings everyone together in the end. As it does with its own complex ecosystem, the Leviathan eventually brings Clankers and Darwinists together to work for their own common good—and that right there is worth the title in its own right.