pouty
Looking sulky with lips pushed out in annoyance.
Pouty describes someone whose face shows they're sulking or unhappy, especially by pushing out their lower lip. When you see a pouty expression, the person looks like they're on the verge of complaining or about to say “that's not fair!”
Picture a younger sibling who didn't get the toy they wanted: their bottom lip sticks out, their mouth turns down at the corners, and their whole face broadcasts disappointment. That's being pouty. Adults can be pouty too, though it usually looks more childish when they do it.
The word comes from pout, which means to push your lips forward in this sulky way. Someone might get pouty when they don't get picked for a team, when they have to leave a party early, or when their friend can't come over to play. Being pouty is different from feeling genuinely sad about something serious. It's more about showing displeasure over small disappointments or not getting your way.
You might describe someone as having pouty lips even when they're not actually sulking. This just means their lips naturally look full or stick out slightly, which some people consider good-looking.