BLISTER (a word found in many forms in Teutonic languages, cf. Ger. Blase; it is ultimately connected with the same root as in "blow," cf. "bladder"), a small vesicle filled with serous fluid raised on the skin by a burn, by rubbing on a hard surface, as on the hand in rowing, or by other injury; the term is also used of a similar condition of the skin caused artificially, as a counter-irritant in cases of inflammation, by the application of mustard, of various kinds of fly (see Cantharides) and of other vesicatories. Similar small swellings, filled with fluid or air, on plants and on the surface of steel or paint, etc., are also called "blisters."
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)