caus·tic·i·ty \kȯˈstisəd.ē, -ətē, -i\noun (-es) Etymology: French causticité, from Latin causticus + French -ité -ity 1.: the quality or state of being caustic : corrosiveness < the causticity of potash > 2.: dry tart sharpness especially of biting wit < the causticity of his retort >