What is the German term for blister?

The term "Blase" is the correct German translation for "blister." This word is commonly used to refer to a fluid-filled bump on the skin, which is a definition that aligns with how "blister" is understood in English.

In the context of the other terms, "Ausbeulung" typically refers to a bulge or a swelling, which does not specifically denote the same medical or skin-related context as "blister." "Buchse" translates to "socket" or "bushing," which relates to mechanical or electrical components rather than skin conditions. Lastly, "Grat" means "burr" or "ragged edge," usually in a reference to materials or surfaces, which is unrelated to the blister concept. Therefore, "Blase" stands out as the appropriate choice for the translation of "blister."