puff up phrasal verb (see also puff)

1. to become bigger by increasing the amount of air inside, or to make something bigger in this way:
The pastry will puff up while it bakes.
puff something ↔ up
Birds puff up their feathers to keep warm.

2. if a part of your body puffs up, it swells painfully because of injury or infection:
My eye had puffed up because of a mosquito bite.

[TahlilGaran] Dictionary of Contemporary English ▲