Physics The temperature and pressure at which the liquid and gaseous phases of a pure substance become unstable and fluctuate locally within the substance. The critical point of water is at a temperature of 374°C (705.2°F) and a pressure of 218 atmospheres, at which point it becomes opaque. Compare triple point.
A maximum, minimum, or point of inflection of a curve.
A point at which the derivative of a function is zero, infinite, or undefined.