A blister is a fluid-filled bubble people get where something rubs or burns the skin. Common causes are wearing fancy new shoes, playing sports, and trying to cook bananas flambé. Having a blister is no fun.
A blister is a round raised area caused by repeated friction or rubbing. A second-degree burn can also cause a blister. A blister isn’t always a human problem. Plants can get blisters, and sometimes air bubbles on the surface of a painted wall or a shellacked table are called blisters. The verb blister means to form a blister. The Old French root word is blestre, "lump or bump."