Blistered is the past and adjective form of blister. It means blisters have formed, or something has made them form. A blister is a small raised bubble on the skin, usually filled with clear liquid, after rubbing, a burn, or a long walk in hard shoes: her heels blistered on the hike; blistered skin. Paint or a wall can blister too, when heat or damp lifts it into little bubbles. Cooks also blister vegetables — peppers, tomatoes — in a very hot pan until the skin bubbles and blackens in spots; that use is ordinary in recipes, not fancy. The word itself is everyday English. It is not the same as blistering in “a blistering attack,” which means very harsh, though both sit on the same family.