caustics >> /ˈkɔːstɪk/
Definition: [noun] A caustic substance.
Example: Spent grain, yeast, ethanol, and acids and caustics used for cleaning are all sent out to be used for feed for cattle or reprocessed and reused industrially.
Definition: [noun] A caustic surface or curve.
Example: Nevertheless, this elucidation of the generic discontinuous change has shed light upon many optical phenomena where caustics and diffraction occur.
Definition: [adjective] Able to burn or corrode organic tissue by chemical action.
Example: a caustic cleaner
Definition: [adjective] Sarcastic in a scathing and bitter way.
Example: the players were making caustic comments about the refereeing
Definition: [adjective] Formed by the intersection of reflected or refracted parallel rays from a curved surface.
Example: In On burning mirrors Diocles also studies the problem of finding a mirror such that the envelope of reflected rays is a given caustic curve or of finding a mirror such that the focus traces a given curve as the Sun moves across the sky.