Famously means in a way that is widely known or recognized by many people. When something happens famously, lots of people know about it. Benjamin Franklin is famously associated with flying a kite in a thunderstorm (though historians debate whether he actually did it). The Titanic famously struck an iceberg on its maiden voyage. Albert Einstein is famously quoted as saying things about imagination and curiosity.

The word often introduces facts or stories that have become part of common knowledge. You might say “Thomas Edison famously tried thousands of materials before finding the right filament for the light bulb” or “The ancient city of Pompeii was famously preserved by volcanic ash.” When you use famously, you're signaling that this is something lots of people recognize or remember.

Sometimes people use it with a touch of irony. If two classmates are famously competitive with each other, everyone in school knows about their rivalry. If your uncle is famously terrible at remembering birthdays, the whole family jokes about it. The word doesn't always mean celebrated or admired; it just means the fact is well-known in that context.