caustic

caustic any strongly corrosive chemical substance, especially one that attacks organic matter. A caustic alkali is a metal hydroxide, especially that of an alkali metal; caustic soda is sodium hydroxide, and caustic potash is potassium hydroxide. Silver nitrate is another caustic substance; it is sometimes called lunar caustic. Most inorganic acids, e.g., sulfuric acid, are caustic, especially when concentrated.

caustic (kaw-stik) n. an agent, such as silver nitrate, that destroys tissue. Caustic agents may be used to remove dead skin, warts, etc.

caustic In optics, light focused by reflection from or refraction through a curved object. For example, when a magnifying glass is used to burn a piece of paper, the intense point of focused light at the paper's surface forms a caustic. Ray-tracing algorithms in computer graphics typically have difficulty correctly detecting and handling this phenomenon. An example might be the form of the sunlight on the bottom of a swimming pool when there are ripples on the surface of the water that focus the light into caustics.