critical point

[krit-i-kuhl point]

noun

1. Physics.,  the point at which a substance in one phase, as the liquid, has the same density, pressure, and temperature as in another phase, as the gaseous.

   The volume of water at the critical point is uniquely determined by the critical temperature.

2. Mathematics.

   1. (of a function of a single variable) a point at which the derivative of the function is zero.

      One critical point, at x = 0, is a decreasing function for positive x.

   2. (of a function of several variables) a point at which all partial derivatives of the function are zero.

      Find and classify all the critical points of the given function.

critical point

noun

1. physics

   1. the point on a phase diagram that represents the critical state of a substance

   2. another name for critical state

2. maths the US name for stationary point

critical point

1. 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.

2. Physics,  Compare triple point

3. Mathematics

   1. A maximum, minimum, or point of inflection of a curve.

   2. A point at which the derivative of a function is zero, infinite, or undefined.

Word History and Origins

Origin of critical point¹

First recorded in 1875–80

Related Words

• turning point