Infamous means famous for something bad. While “famous” simply means well-known, infamous means well-known for negative reasons: crimes, scandals, disasters, or terrible behavior.

Al Capone was an infamous gangster in 1920s Chicago, known for violence and bootlegging. The Titanic's sinking became an infamous disaster in maritime history. A student who pulls cruel pranks might become infamous around school, not admired but recognized for the wrong reasons.

The word carries a sense of notoriety, meaning people know about you but wish they didn't have to. Benedict Arnold became infamous in American history for betraying his country during the Revolutionary War. The Boston Molasses Flood of 1919 was an infamous accident when a huge tank of molasses burst and flooded the streets.

Sometimes people confuse infamous with famous, but the difference matters. A famous inventor changed the world for the better. An infamous criminal changed it for the worse. Both are widely known, but only one is remembered with respect. When something or someone is described as infamous, expect a story of wrongdoing, failure, or tragedy that people still talk about years later.