Caustic

kaws′tik, adj. burning: ( fig. ) bitter, severe, cutting: ( math. ) noting an envelope of rays of light proceeding from a fixed point and reflected ( catacaustic ) or refracted ( diacaustic ) by a surface or a curve.— n. a substance that exerts a corroding or disintegrating action on the skin and flesh.— adv. Caus′tically .— n. Caustic′ity , quality of being caustic.— Caustic alkali ( chem. ), a name given to the hydrates of pota ium and sodium, called caustic potash and caustic soda respectively; Caustic ammonia , ammonia as a gas, or in solution; Caustic lime , quicklime.— Common caustic , potash; Lunar caustic , nitrate of silver in sticks for surgical use. [L.,—Gr. kaustikos — kai-ein , kaus-ein , to burn.]