A good way to describe what "originalism" means is to contrast it with activism, and the best definition of "activism" came from Thurgood Marshall, who when asked by one of his clerks to describe his judicial philosophy said,
"You do what you think is right and let the law catch up."
And that's it, in a nutshell. And originalist will follow the law even if he/she believe it to be wrong. And activist won't.