(chemistry) A measure of the relative concentrations of the reactants and products of a reversible reaction at equilibrium

(computing theory) A real number that informally represents the probability that a randomly-constructed program will halt.

(logic) One of a set of letters or symbols which are assigned fixed truth values independently of any interpretation or valuation, and each of which qualifies as a prime formula of their language.

(mathematics) The transcendental number e^(𝜋√), an almost integer, discovered in 1859 by mathematician Charles Hermite.

(mathematics) The problem of deciding whether a given expression is equal to zero.

(programming) An identifier that is substituted by a pre-defined value prior to compilation.

(chemistry) The dependence of the rate of a reaction on the concentrations of the reactants

(mathematics) The value e^π (approximately 23.140692632779), known to be transcendental.

(number theory) The finite value, denoted by B₂, to which the sum of the reciprocals of the twin primes converge, according to Brun's theorem.

(chemistry, physics) A measure of the screening / shielding of an electron from the charge of the nucleus by other, inner electrons