Plump describes something round, full, and slightly fat in a pleasant, healthy way. A plump strawberry is juicy and ripe, swollen with sweetness. Plump sofa cushions are soft and inviting, filled just right for comfortable sitting. When your grandmother says the Thanksgiving turkey looks nice and plump, she means it's well-fed and will make a good meal.

The word usually suggests something appealing rather than excessive. Plump cheeks on a baby look healthy and adorable. Plump grapes are the ones you reach for first because they look fresh and full of flavor. Writers often describe plump pillows or plump tomatoes to help readers imagine something satisfying and abundant.

As a verb, to plump means to make something fuller or rounder. You might plump up the pillows on your bed by fluffing them with your hands. Birds plump up their feathers by puffing them out to stay warm.

The word can describe people too, though you should be thoughtful about this. While “plump” isn't meant as an insult, talking about someone's body can make them uncomfortable. Context and tone matter quite a bit when using words that describe how people look.