the physical condition, specified by pressure or density, at which a substance at its critical temperature can exist as a liquid and vapor in equilibrium
See critical point in American Heritage Dictionary 4
noun
Physics The temperature and pressure at which the liquid and gaseous phases of a pure stable substance become identical. Also called critical state.
Mathematics
a. A maximum, minimum, or point of inflection of a curve.
b. A point at which the derivative of a function is zero, infinite, or undefined.