From Longman Dictionary of Contemporary Englishpuff up phrasal verb1 INCREASE IN NUMBER OR AMOUNTto 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 MIif 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. → puff→ See Verb table
