Unfunny means failing to be funny, or being awkwardly bad at attempting humor. When a joke falls flat and nobody laughs, that joke was unfunny. When a comedian tells stories that make the audience groan instead of giggle, their act was unfunny.

The word usually describes something that tried to be funny but failed. An unfunny joke might rely on a punchline that doesn't make sense, or keep going so long that any humor drains away. A movie described as unfunny probably filled itself with silly scenes that just didn't work.

Sometimes people use unfunny to describe jokes about serious topics that shouldn't be laughed at. If someone makes light of another person's real struggles or pain, you might say “That's not funny” or “That's really unfunny.” In this case, the word carries a sharper edge: it means inappropriate or even cruel, beyond just unsuccessful at humor.

The opposite of unfunny is, of course, funny or hilarious. Unfunny feels stronger than simply “not funny” because it suggests active failure rather than mere absence of humor, like the difference between a blank wall and a wall with truly ugly wallpaper.