What adjective describes something that is able to burn or eat away by chemical action?

The term that describes something capable of burning or eating away by chemical action is "caustic." This adjective specifically refers to substances that can cause destruction or corrosion through a chemical process, such as strong acids or bases. In contrast, the other adjectives do not convey this meaning: "harmless" suggests that something poses no risk or danger, "blunt" refers to an object lacking a sharp edge or point, and "gentle" indicates a soft or mild manner that does not imply any abrasive or destructive qualities. Therefore, "caustic" is the correct and precise term for substances that chemically corrode or burn materials.