A<unk>  is a small pocket of body fluid (lymph, serum, plasma, blood, or pus) within the upper layers of the skin, usually caused by forceful rubbing (friction), burning, freezing, chemical exposure or infection. Most<unk> s are filled with a clear fluid, either serum or plasma. However,<unk> s can be filled with blood (known as "blood<unk> s") or with pus (for instance, if they become infected). The word<unk> " entered English in the 14th century. It came from the Middle Dutch and was a modification of the Old French , which meant a leprous nodule—a rise in the skin due to leprosy. In dermatology today, the words vesicle and bulla refer to<unk> s of smaller or greater size, respectively. To heal properly, a<unk>  should not be popped unless medically necessary. If popped, the excess skin should not be removed because the skin underneath needs the top layer to heal properly.
Blister
Oscar 
Saddle sore
Sequela
Pouchitis
Phlegmon
Chilblains
Eschar