(physics) A universal scaling factor for all spectroscopic transitions.

The amount of incoming solar radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays.

(mathematics) A function whose value is the same for all the elements of its domain.

(mathematics) A characteristic of an exponential function, represented by τ in the function:

(calculus) An unspecified constant term added to a particular antiderivative to make it represent its whole family of antiderivatives, usually denoted with C.

(physics) A term added by Albert Einstein to his equations of general relativity in order to account for a supposed static universe, since used to describe vacuum energy as a form of dark energy.

(logic) A word or phrase which has an invariant logical meaning and which is useful for forming argument forms.

plural of absolute constant

(crystallography) The constant distance between unit cells in a crystal lattice. It may be different in each direction, thus a crystalline substance may have up to three lattice constants.

(mathematics) A constant that maintains the same value wherever it occurs; such as π. / Used other than figuratively or idiomatically: see absolute, constant.