A lunk is a big, clumsy, often not-too-bright person. If someone calls you a lunk, they're saying you're awkward or slow-witted, like a character in a cartoon who keeps bumping into things or missing obvious jokes.

The word often appears as lunkhead, which means the same thing but sounds even more insulting. You might hear someone say, “Don't be such a lunkhead!” when a friend does something foolish or fails to understand something simple.

Lunk isn't usually meant as a serious insult. It's more of a lighthearted way to tease someone who's being dopey or clumsy in the moment. A basketball player who trips over his own feet might get called a lunk by his teammates, even though everyone knows he's actually coordinated. The word suggests someone is being goofy or dense right now, not that they're actually unintelligent.

You'll sometimes see the word in older books and movies, where a big, bumbling character gets described as a lunk. It's the kind of word that sounds like what it means: heavy, blunt, and a little awkward, just like the person it's describing.