Ah... then I would definitely use Google. If your title is a phrase (not a single word) put the phrase in quotes. ie: "The Big Disaster"
But why worry about it? If your book's title is such that it is hard for publishers to accept, but they like the story, they'll just suggest a new title. They may not even suggest, but just change it. Really, all you care about is getting loads of money and winning the Pulitzer (and maybe the Nobel, Nebula, Hugo, etc) anyway.