Heretofore means up until now, or before this moment. It's a formal word you'll find in legal documents, historical writing, and speeches when someone wants to mark a clear dividing line between the past and present.

When a scientist announces a discovery of a species heretofore unknown to science, she means no one had identified it before now. When a contract states that certain rules are “heretofore null and void,” it means those rules are treated as if they never had legal effect.

The word carries a sense of formality and importance. You wouldn't say “I've heretofore liked pizza.” You'd just say “I've always liked pizza” or “Until now, I liked pizza.” But in serious writing, heretofore signals that what came before was significant and that something meaningful is changing. A judge might note that a law heretofore permitted something that's now restricted. A historian might describe attitudes that were heretofore common but later shifted.

Think of heretofore as drawing a line in time: everything on one side happened before, and now something new begins. It's similar to “previously” or “until this point,” but more formal and often more dramatic.