caustics

In a chemical context, this term refers to highly corrosive substances, such as sodium hydroxide, that destroy living tissue. It carries a strong connotation of danger and toxicity, typically appearing in technical, industrial, or laboratory settings. It is distinct from "acidic" in that caustics can be either strongly acidic or strongly alkaline, provided they cause chemical burns.

In optics, the term describes the concentrated patterns of light seen at the bottom of a pool or through a glass of water. This usage is specialized and primarily found in physics, computer graphics, and photography to describe the specific geometry of refracted light rays. This sense is almost always used in the plural to describe the overall effect of multiple light patterns.