Someone surly is bad-tempered, unfriendly, and rude in a grumpy, growling sort of way. A surly store clerk might grunt instead of greeting customers, or roll their eyes when asked a question. A surly neighbor might snap “What do you want?” when you knock on their door.

The word suggests more than just being in a bad mood. Surly people act deliberately unfriendly, almost hostile, making others feel unwelcome. They seem to want you to know they're irritated, showing their displeasure through gruff behavior and sharp responses.

You might encounter surly behavior from someone having a terrible day, but some people develop a surly manner that becomes their regular way of treating others. A surly dog might growl and refuse to let anyone pet it. A surly character in a story might grumble and complain constantly.

When someone's being surly, they're showing their bad mood to everyone around them, making situations more unpleasant than they need to be.