Water blister
A blister with clear watery contents that is not purulent (does not contain pus) and is not sanguineous (does not contain blood). A blister is medically termed a vesicle. One that is more than 5 mm in diameter with thin walls and is full of watery fluid is called a bulla or a bleb. The word "blister" entered English in the 14th century. It came from the Middle Dutch "bluyster", blister and was a modification of the Old French "blostre" which meant a leprous nodule — a rise in the skin due to leprosy.
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water blister n a blister with a clear watery content that is not purulent or sanguineous
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a blister with clear watery contents.
Medical dictionary.
2011.