The noun BLISTER means a raised area on the skin that contains clear liquid and that is caused by injury to the skin:
My left shoe is rubbing against my heel. I’m going to develop a blister.
At the end of the day I had blisters all over my feet.
I had a blister on my hand because I had been using a hammer for two hours.
You don’t have to go to see your doctor, it’s just a blister.
If your blister breaks, cover it with antibiotic ointment.
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